Cargo scanning system

ABSTRACT

The present invention is directed to a portable inspection system for generating an image representation of target objects using a radiation source. A detector array having a first configuration and a second configuration is connected to a housing and at least one source of radiation. The radiation source is capable of being transported to a site by a vehicle and of being positioned separate from the housing. The radiation source is housed in a radiation source box and movable within the radiation source box using an actuator. The actuator is operably connected to the radiation source and provides a translational energy that moves the radiation source between an operational position and a stowed position.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention relies on, for priority, U.S. Provisional PatentApplication No. 60/984,786, entitled “Cargo Scanning System” and filedon Nov. 2, 2007. In addition, the present invention is acontinuation-in-part of U.S. patent application Ser. No. 11/948,814,entitled, “Single Boom Cargo Scanning System”, filed on Nov. 30, 2007now U.S. Pat. No. 7,517,149, which is a continuation of U.S. patentapplication Ser. No. 10/915,687, now U.S. Pat. No. 7,322,745, entitled,“Single Boom Cargo Scanning System”, filed on Aug. 9, 2004, whichfurther relies on, for priority, U.S. Provisional Patent Application No.60/493,935, filed on Aug. 8, 2003. U.S. patent application Ser. No.10/915,687 is a continuation-in-part of U.S. patent application Ser. No.10/201,543, entitled “Self-Contained Portable Inspection System andMethod”, filed on Jul. 23, 2002 and now U.S. Pat. No. 6,843,599. All ofthe aforementioned applications and patents are incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates generally to a self-contained mobileinspection system and method and, more specifically, to improved methodsand systems for detecting materials concealed within a wide variety ofreceptacles and/or cargo containers. In particular, the presentinvention relates to improved methods and systems for inspectingreceptacles and/or cargo containers using a radiation source orradiation sources, having at least two different energies allowing formore efficient, complete scanning and improved detection. In addition,the present invention relates to an improved radiation source boxwherein the at least one radiation source can be moved when ready forscanning, allowing for improved safety and efficiency.

BACKGROUND OF THE INVENTION

X-ray systems are used for medical, industrial and security inspectionpurposes because they can cost-effectively generate images of internalspaces not visible to the human eye. Materials exposed to X-rayradiation absorb differing amounts of X-ray radiation and, therefore,attenuate an X-ray beam to varying degrees, resulting in a transmittedlevel of radiation that is characteristic of the material. Theattenuated radiation can be used to generate a useful depiction of thecontents of the irradiated object. A typical single energy X-rayconfiguration used in security inspection equipment may have afan-shaped or scanning X-ray beam that is transmitted through the objectinspected. The absorption of X-rays is measured by detectors after thebeam has passed through the object and an image is produced of itscontents and presented to an operator.

Trade fraud, smuggling and terrorism have increased the need for suchnon-intrusive inspection systems in applications ranging from curbsideinspection of parked vehicles to scanning in congested or high-trafficports because transportation systems, which efficiently provide for themovement of commodities across borders, also provide opportunities forthe inclusion of contraband items such as weapons, explosives, illicitdrugs and precious metals. The term port, while generally accepted asreferring to a seaport, also applies to a land border crossing or anyport of entry.

With an increase in global commerce, port authorities require additionalsea berths and associated container storage space. Additional spacerequirements are typically met by the introduction of higher containerstacks, an expansion of ports along the coastline or by moving inland.However, these scenarios are not typically feasible. Space is generallyin substantial demand and short supply. Existing ports operate under aroutine that is not easily modified without causing disruption to theentire infrastructure of the port. The introduction of new procedures ortechnologies often requires a substantial change in existing portoperating procedures in order to contribute to the port's throughput,efficiency and operability.

With limited space and a need to expand, finding suitable space toaccommodate additional inspection facilities along the normal processroute remains difficult. Additionally, selected locations are notnecessarily permanent enough for port operators to commit to. Moreover,systems incorporating high-energy X-ray sources, or linear accelerators(LINAC), require either a major investment in shielding material(generally in the form of concrete formations or buildings) or the useof exclusion zones (dead space) around the building itself. In eithercase the building footprint is significant depending upon the size ofcargo containers to be inspected.

A mobile inspection system offers an appropriate solution to the needfor flexible, enhanced inspection capabilities. Because the system isrelocatable and investing in a permanent building in which toaccommodate the equipment is obviated, site allocation becomes less ofan issue and introducing such a system becomes less disruptive. Also, amobile X-ray system provides operators, via higher throughput, with theability to inspect a larger array of cargo, shipments, vehicles, andother containers.

An example of a mobile X-ray inspection system is provided in U.S. Pat.No. 5,692,028 assigned to Heimann Systems. The '028 patent discloses anX-ray examining system comprising a mobile vehicle and an X-rayexamining apparatus for ascertaining contents of an object, saidapparatus including a supporting structure mounted on the mobilevehicle; said supporting structure being portal-shaped for surroundingthe object on top and on opposite sides thereof during X-rayexamination; said supporting structure including (i) a generallyvertical column mounted on said vehicle and rotatable relative to saidvehicle about a generally vertical axis; said column having an upperend; (ii) a generally horizontal beam having opposite first and secondend portions; said beam being attached to said upper end at said firstend portion for rotation with said column as a unit for assuming aninoperative position vertically above said mobile vehicle and anoperative position in which said beam extends laterally from saidvehicle; and (iii) an arm pivotally attached to said second end portionof said beam for assuming an inoperative position in which said armextends parallel to said beam and an operative position in which saidarm extends generally vertically downwardly from said beam; an X-raysource for generating a fan-shaped X-ray beam; said X-ray source beingcarried by said vehicle; and an X-ray detector mounted on saidsupporting structure; said X-ray examining system being adapted totravel along the object to be examined while irradiating the object anddetecting the X-rays after passage thereof through the object.

U.S. Pat. No. 5,764,683 assigned to AS&E discloses a device forinspecting a cargo container, the device comprising: a bed moveablealong a first direction having a horizontal component; a source ofpenetrating radiation, mounted on the bed, for providing a beam; amotorized drive for moving the bed in the first direction; at least onescatter detector mounted on the bed, the at least one scatter detectorhaving a signal output; and a transmission detector for detectionpenetrating radiation transmitted through the cargo container such thatthe beam is caused to traverse the cargo container as the bed is movedand the at least one scatter detector and the transmission detector eachprovide a signal for characterizing the cargo container and any contentsof the cargo container.

U.S. Pat. No. 6,252,929 assigned to AS&E claims a device for inspectinga cargo container with penetrating radiation, the device comprising: abed that is reversibly moveable along a direction having a horizontalcomponent; a source of penetrating radiation, mounted on the bed forproviding a beam having a central axis, the central axis beingpredominantly horizontal; a motorized drive for moving the bed in thefirst direction; at least one scatter detector mounted on the bed, eachscatter detector having a signal output; so that, as the bed is movedforward and backward along the direction, the beam is caused to traversethe cargo container as the bed is moved and each scatter detectorprovides a signal for characterizing the cargo container and anycontents of the cargo container.

U.S. Pat. No. 6,292,533, also assigned to AS&E, claims a system forinspecting a large object with penetrating radiation during motion ofthe system in a scan direction, the system comprising: a vehicle havingwheels and an engine for propelling the vehicle on highways; a boomhaving a proximal end rotatable about a point on the vehicle and adistal end, the boom deployed transversely to the scan direction forstraddling the object during operation of the system; a source ofpenetrating radiation coupled to the vehicle for providing a beam sothat the beam is caused to irradiate a first side of the object as thevehicle is moved in the scan direction; and at least one detectorcoupled to the vehicle on a side of the object opposing the first side,the at least one detector having a signal output, the at least onedetector providing a signal for imaging the object.

U.S. Pat. No. 5,903,623, assigned to AS&E, claims a device, forinspecting a large object with penetrating radiation, the devicecomprising: a self-propelled vehicle capable of on-road travel; a sourceof penetrating radiation, mounted on the vehicle, for providing a beamof penetrating radiation; a beam stop for absorbing the beam ofpenetrating radiation after traversal of the object; and at least onedetector coupled to the vehicle, the at least one detector having asignal output so that the beam is caused to traverse the object in afirst direction as the vehicle is moved and the signal outputcharacterizes the object.

In addition to the features described above, conventional relocatableinspection systems generally comprise at least two booms, wherein oneboom will contain a plurality of detectors and the other boom willcontain at least one X-ray source. The detectors and X-ray source workin unison to scan the cargo on the moving vehicle. In conventionalsingle boom relocatable inspection systems, the X-ray source is locatedon a truck or flatbed and the detectors on a boom structure extendingoutward from the truck.

The aforementioned prior art patents are characterized bymoving-scan-engine systems wherein the source-detector system moves withrespect to a stationary object to be inspected. Also, the detectors andthe source of radiation are either mounted on a moveable bed, boom or avehicle such that they are integrally bound with the vehicle. Thislimits the flexibility of dismantling the entire system for optimumportability and adjustable deployment to accommodate a wide array ofdifferent sized cargo, shipments, vehicles, and other containers. As aresult these systems can be complicated to deploy and pose severaldisadvantages and constraints.

For example, in a moving-scan-engine system the movement of the sourceand detector, relative to a stationary object, may cause lateral twistand lift and fall of the detector or source, due to movement of thescanner over uneven ground, inducing distortions in the scanned imagesand faster wear and tear of the scanner system. Systems where the weightof the detector or source is held on a boom require high structuralstrength for the boom in order to have the boom stable for imagingprocess, thereby adding more weight into the system. Such systems thatrequire a detector-mounted boom to unfold during deployment may cause anunstable shift of the center of gravity of the system off the base,causing the system to tip over. Further, in the case ofmoving-scan-engine systems using a “swing arm” boom approach, the driverdriving the scanner truck is unable to gauge the possibility of hittingthe detector box, mounted on a boom, with a vehicle under inspection(VUI), as the detector box is on the other side of the VUI duringscanning and not visible to the driver.

Additionally, with moving-scan-engine systems, the truck supporting thescanner system is always required to move the full weight of the scannerregardless of the size and load of the VUI, putting greater strain onthe scanning system. Further, because of the integrated nature of priorart systems, swapping detector and radiation systems between scanningsystems is not feasible. In terms of throughput, prior art systems needadditional operational systems that greatly multiply the cost ofoperation to increase the number of VUI to be handled. Alsodisadvantageous in conventional systems is that they suffer from a lackof rigidity, are difficult to implement, and/or have smaller fields ofvision.

Accordingly, there is need for improved inspection methods and systemsbuilt into a fully self-contained, over-the-road-legal vehicle that canbe brought to a site and rapidly deployed for inspection. The improvedmethod and system can, therefore, service multiple inspection sites andset up surprise inspections to thwart contraband traffickers whotypically divert smuggling operations from border crossings that havetough interdiction measures to softer crossings with lesser inspectioncapabilities. Moreover, there is an additional need for methods andsystems that require minimal footprint to perform inspection and thatuse a sufficient range of radiation energy spectrum to encompass safeand effective scanning of light commercial vehicles as well assubstantially loaded 20-foot or 40-foot ISO cargo containers. It isimportant that such scanning is performed without comprising theintegrity of the cargo and should ideally be readily deployable in avariety of environments ranging from airports to ports of entry where asingle-sided inspection mode needs to be used due to congestedenvironments. Such needs are addressed in co-pending U.S. patentapplication Ser. No. 10/201,543, entitled “Self-Contained PortableInspection System and Method”, which is herein incorporated by referencein its entirety.

Improved methods and systems are additionally needed to keep therelative position between the radiation source and detector fixed toavoid distortion in images caused by the movement of scanner and/ordetectors over uneven ground or due to unstable structures. Moreover,there is a need for improved methods and systems that can providecomprehensive cargo scanning in portable and stationary settings.Specifically, methods and systems are needed in which a single boom isemployed for generating quality images for inspection. Further, thesystem should be mounted on a relocatable vehicle, capable of receivingand deploying the boom.

What is also needed is a single boom cargo scanning system that enablesquick and easy deployment, rigidity and tight alignment of the radiationsources and detectors, and a narrow collimated radiation beam, thusallowing for a smaller exclusion zone. In addition, what is needed is anoptimal scanning system design that allows for the radiation source tobe closer to the Object under Inspection (“OUI”), thereby allowing forhigher penetration capability and complete scanning of the targetvehicle without corner cutoff. Such needs are addressed in co-pendingUnited States patent application, entitled “Single Boom Cargo ScanningSystem” and filed on Aug. 8, 2004, which is herein incorporated byreference in its entirety.

What is also needed is a system that employs a radiation source orradiation sources having at least two different energies for betterscanning resolution and enhanced detection capability. What is alsoneeded is a rapidly deployable dual energy inspection system which usesa single detector array to separately detect low atomic number and highatomic number threat items.

What is also needed is an improved radiation source box wherein theradiation source has translational movement, allowing for improvedsafety and efficiency.

What is also needed is a method and system for safely transporting aradiation source box and actuator mechanism with ease and a minimalnumber of operators. What is also needed is a method and system fordirectly installing a radiation source box on a truck boom with ease.

SUMMARY OF THE INVENTION

The inspection methods and systems of the present invention areportable, mobile, rapidly deployable, and capable of scanning a widevariety of receptacles cost-effectively and accurately on unevensurfaces. In a first embodiment, a self-contained inspection systemcomprises an inspection module that, in a preferred embodiment, is inthe form of a mobile trailer capable of being towed and transported toits intended operating site with the help of a tug-vehicle.

In one embodiment, the portable inspection system for generating animage representation of target objects using a radiation source,comprises a housing connected to a vehicle, a detector array having afirst configuration and a second configuration wherein said array isconnected to the housing, and at least one source of radiation whereinsaid radiation source is capable of being transported to a site by saidvehicle and of being positioned separate from the housing, wherein saidradiation source is housed in a radiation source box and movable withinthe radiation source box using an actuator wherein the actuator isoperably connected to the radiation source and wherein the actuatorprovides a translational energy that moves the radiation source betweenan operational position and a stowed position.

In another embodiment, the portable inspection system for generating animage representation of target objects using a radiation source,comprises a foldable boom comprising a first vertical portion, which isphysically attached to said vehicle, a first horizontal portion, and asecond vertical portion; a first detector array housing physicallyattached to the first horizontal portion of the foldable boom, whereinsaid first detector array housing contains a plurality of detectors; asecond detector array housing physically attached to the first verticalportion of the foldable boom wherein the second detector array housingcontains a plurality of detectors and is foldable independent of saidfirst vertical portion of the foldable boom; and at least one source ofradiation wherein said radiation source is housed in a radiation sourcebox and movable within the radiation source box using an actuator,wherein the actuator is operably connected to the radiation source,wherein the actuator provides a translational energy that moves theradiation source between an operational position and a stowed position,and wherein the radiation source box is securely attached to a distalend of the second vertical portion of said boom.

Optionally, the radiation source is movable in a horizontal or verticaldirection. The actuator is an electric solenoid or a pneumatic solenoid.The radiation source is offset from a beam port aperture defined by theradiation source box when in a stowed position. The radiation source isoffset from a beam port aperture by three inches. The radiation sourceis encapsulated in a shield when offset from a beam port aperture. Theshield comprises tungsten. The radiation source is aligned with a beamport aperture defined by the radiation source box when in an operationalposition. The radiation source box further comprises a return mechanismfor ensuring that the radiation source is in a safe position when thereis no power being delivered to the system. The radiation source boxfurther comprises at least one safety feature for indicating a status ofthe radiation source. The safety feature is electrical and furthercomprises a light, or audible and further comprises a beeping alarm, ormechanical and further comprises a flag.

Optionally, the system includes a hydraulic system to move the boom. Thefirst and second detector arrays comprise detectors and wherein saiddetectors are angled at substantially 90 degrees relative to a focalpoint of said radiation source. The radiation source comprises at leasta first energy and a second energy, wherein the first energy is a lowenergy and wherein the second energy is a high energy.

In another embodiment, the present invention is a method for inspectingobjects using a portable inspection system that generates an imagerepresentation of a target object using at least one radiation source,comprising the steps of: transporting a detector array, a foldable boom,and at least one source of radiation to an operation site using avehicle, wherein the foldable boom comprises a first vertical portion,which is physically attached to said vehicle, a first horizontalportion, and a second vertical portion; wherein the detector array ishoused within a first detector array housing physically attached to thefirst horizontal portion of the foldable boom and a second detectorarray housing physically attached to the first vertical portion of thefoldable boom, wherein the second detector array housing is foldableindependent of said first vertical portion of the foldable boom, andwherein the radiation source is housed in a radiation source box whichis fixedly attached to a distal end of the second vertical portion ofsaid boom; creating a detection region by moving said first horizontalportion of the boom into a substantially perpendicular position relativeto said vehicle and by moving said second vertical portion of the boominto a substantially parallel position relative to said first verticalportion; moving the vehicle passed the target object such that saidtarget object passes through said detection region; using an actuator tomove the radiation source so that it is aligned with a beam portaperture defined by the radiation source box; activating said radiationsource; exposing the target object to radiation emitted from theradiation source wherein the exposing step results in secondaryradiation; and detecting secondary radiation by the detector array.

The aforementioned and other embodiments of the present invention shallbe described in greater depth in the drawings and detailed descriptionprovided below.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will beappreciated, as they become better understood by reference to thefollowing Detailed Description when considered in connection with theaccompanying drawings, wherein:

FIG. 1 provides a perspective view of an exemplary self-containedinspection system of the present invention;

FIG. 2 depicts one embodiment of a hydraulic lift mounted on atug-vehicle and the unloading of a radiation source;

FIG. 3 is a side elevation view of one embodiment of the portableinspection trailer;

FIG. 4 is a side elevation view of one embodiment of the presentinvention in operational mode;

FIG. 5 is a side view of a second embodiment of the present system;

FIG. 6 is a second embodiment of an inspection trailer;

FIG. 7 is one embodiment of an inspection trailer, depicting the use ofa hydraulic system;

FIG. 8 is top plan view of a second embodiment of the present inventionduring operation;

FIG. 9 a is a schematic view of an exemplary hydraulic system used forautomatically unfolding the detector panels;

FIG. 9 b is a second view of an exemplary hydraulic system used forautomatically unfolding the detector panels;

FIG. 10 is a flowchart of one exemplary process for setting-up thesystem of the present invention;

FIG. 11 is a flowchart of one exemplary process for deploying thedetector system;

FIG. 12 is a view of an exemplary radiation source;

FIG. 12 a is a block diagram of one embodiment of the radiation sourcesystem of the present invention, including associated peripheraldevices;

FIG. 12 b is one embodiment of an outer enclosure of the radiationsource box of the present invention, further illustrating safetyindicators;

FIG. 12 c is an illustration of one embodiment of the radiation sourcebox of the present invention, mounted on a truck boom;

FIG. 12 d is an illustration of the internal components of the radiationsource box of the present invention;

FIG. 12 e is a detailed illustration of the radiation source box of thepresent invention without the cylindrical housing cover shown in FIG. 12d;

FIG. 12 f is an illustration of an electric solenoid for use with oneembodiment of the radiation source box of the present invention;

FIG. 12 g is an illustration of a pneumatic solenoid for use with oneembodiment of the radiation source box of the present invention;

FIG. 12 h is a cut-away illustration of one embodiment of an actuatormechanism as used in the radiation source box of the present invention;

FIG. 12 i depicts one embodiment of a hinged door for use with theradiation source box of the present invention, which when opened, yieldsaccess to the actuator;

FIG. 12 j is a flowchart showing the operational steps of the radiationsource box system of the present invention;

FIG. 12 k is an illustration of one embodiment of a source transportassembly for transporting and installing the radiation source box on theboom of the scanning system of the present invention;

FIG. 12 m is an illustration of another embodiment of a source transportassembly for transporting and installing the radiation source box on theboom of the scanning system of the present invention;

FIG. 12 n is an illustration of the source transport assembly shown inFIG. 12 m, with the radiation source box installed;

FIG. 12 o is a front-view illustration of the source transport assemblyshown in FIG. 12 m, with the radiation source box installed;

FIG. 12 p is an illustration of the source transport assembly shown inFIG. 12 m, with the radiation source box installed and the boom sourcearm in position for transfer;

FIG. 12 q is a schematic illustration of the source transport bracketassembly with the radiation source box installed, with a shipment cratecover;

FIG. 12 r is an illustration of the source transport bracket with theradiation source box installed, with a shipment crate cover and base;

FIG. 12 s is an illustration of the base of the shipment crate used totransport the radiation source box and bracket assembly;

FIG. 13 is a representation of an exemplary embodiment of the integratedsingle boom cargo scanning system of the present invention;

FIG. 14 is a side view illustration of one embodiment of the vehicle ofthe present invention in a “stowed” position;

FIG. 15 is a top view illustration of one embodiment of the vehicle ofthe present invention in a “stowed” and relocatable position;

FIG. 16 is a side perspective view of the single boom cargo scanningtruck of the present invention in a preferred embodiment;

FIG. 17 depicts the top view of the single boom cargo scanning system ofthe present invention, in a deployed position;

FIG. 18 depicts an exemplary movement of the telescopic arm of thesingle boom cargo scanning truck of the present invention;

FIG. 19 depicts a second exemplary movement of the telescopic arm of thesingle boom cargo scanning truck of the present invention;

FIG. 20 is a rear view illustration of the single boom cargo scanningsystem of the present invention, in a preferred usage;

FIG. 21 depicts the rotating collimation wheel employed in the scanningsystem of the present invention;

FIG. 22 illustrates an embodiment of the detector array as employed inthe single boom cargo scanning system of the present invention;

FIG. 23 is a detailed illustration of one embodiment of the detectorsemployed in the detector array shown in FIG. 10;

FIG. 24 is a detailed illustration of another embodiment of thedetectors employed in the detector array shown in FIG. 10, where thedetectors are arranged in a dual row;

FIG. 25 is a block diagram of an exemplary display and processing unitof the single boom cargo scanning system of the present invention;

FIG. 26 is a flowchart depicting the operational steps of the singleboom cargo scanning system of the present invention upon execution of animage generation program;

FIG. 27 is a schematic representation of a dual energy radiation sourceas employed in one embodiment of the self-contained mobile inspectionsystem of the present invention;

FIG. 28 is a block diagram of an exemplary gamma-ray image processingand display unit of the self-contained mobile inspection system of thepresent invention;

FIG. 29 is a flow chart depicting the operational steps of theself-contained mobile inspection system employing a dual energyradiation source upon the execution of an image generation program; and

FIG. 30 is a top view illustration of the radiation safety exclusionzone and dosage areas surrounding the scanning system of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

The inspection methods and systems of the present invention are mobile,rapidly deployable, and capable of scanning a wide variety ofreceptacles cost-effectively and accurately, with rigidity, ease of use,and a wider field of vision. Reference will now be made in detail tospecific embodiments of the invention. While the invention will bedescribed in conjunction with specific embodiments, it is not intendedto limit the invention to one embodiment. U.S. patent application Ser.Nos. 10/201,543, 10/915,687, 10/939,986, and 11/622,560 are incorporatedherein by reference.

In a first embodiment, FIG. 1 shows a perspective view of an exemplaryself-contained inspection system 100. The system 100 comprises of aninspection module 15 that, in a preferred embodiment, is in the form ofa mobile trailer capable of being towed and transported to its intendedoperating site with the help of a tug-vehicle 10. While the presentinvention is depicted as a tug vehicle 10 connected to a trailer 15, oneof ordinary skill in the art would appreciate that the vehicular portionof the system and inspection module portion of the system could beintegrated into a single mobile structure. The preferred embodiment usesa tug vehicle independent from the inspection module because, asdiscussed later, it adds greater flexibility in how the system is used.In another embodiment, the operator trailer, unit 15, could be aseparate vehicle by itself.

The tug-vehicle 10 can serve as a support and carrier structure for atleast one source of electromagnetic radiation 11; hydraulic lift system12, such as the Hiab lifting cranes along with suitable jigs andfixtures or any other lifting mechanism known in the art, to load andunload the at least one source 11; and a possible radiation shield plate13 on the back of the driver cabin of tug-vehicle 10, to protect thedriver from first order scatter radiation. The inspection trailer 15 ishitched to the tug-vehicle 10 using a suitable tow or hitch mechanism 5such as class I through V frame-mounted hitches; fifth wheel andgooseneck hitches mounted on the bed of a pick-up; a simplepintle-hitch; branded hitches such as Reese, Pull-rite and Hensley orany other means known to one of ordinary skill in the art. The class ofthe hitch indicates the amount of trailer load that it can handle. Forexample, a class I hitch is rated for a trailer load of about 2000pounds whereas a class V hitch is rated for loads greater than 10,000pounds. A typical manually-releasable tow-bar mechanism, disclosed inU.S. Pat. No. 5,727,806 titled “Utility Tow Bar” and assigned to ReeseProducts Inc., comprises a coupler assembly including a hitch ballreceiving socket and cooperating lock. This facilitates selectiveconnection of a tow-bar to the hitch ball of a trailer hitch receivercarried by a towing vehicle. Alternatively, automatic hitches may alsobe used for quick coupling and detaching of the tow truck and trailerwithout manual intervention or attendance.

Referring back to FIG. 1, the inspection or scanning module 15 iscustom-built as a mobile trailer can provide support for a plurality ofdetector arrays 16 and a boom 17 to deploy a power cable to at least onesource of radiation during operation. The trailer 15 also houses anoperator/analyst cabin including computer and imaging equipment alongwith associated power supplies, air conditioning and power generatingequipment in accordance with the understanding of a person of ordinaryskill in the art of X-ray generation. In high energy/high performancesystem, the trailer containing the detector array 16 and boom 17 may bein a different unit from the trailer housing the operator inspectionroom 15. This will allow the operator to avoid being in a high radiationarea and reduce the amount of shielding required for his protection. Inpreferred embodiment, the trailer 15 may additionally include aplurality of leveling or support feet 18, 19 to enable stabilizedimaging when in stationary use.

In order to use the system 100, the inspection trailer 15 is towed tothe inspection site by the tug-vehicle 10. After positioning theinspection trailer 15, the tug-vehicle 10 is detached and movedsubstantially parallel to the trailer 15 and towards the side carryingthe detector system 16. Here, the radiation source box 11 is shifted outof the tug-vehicle 10 and lowered down to the ground by a hydrauliccrane 12 mounted on the tug-vehicle 10. Thus, the source box 11 isplaced laterally opposite to the detector system 16 at a distance thatis suitable to allow an OUI to pass between the source 11 and detector16 during the scanning process. An OUI could be any type of object,including cars, trucks, vans, mobile pallets with cargo, or any othertype of moveable object. During the scanning process, the tug-vehicle10, after lowering down the source 11, is maneuvered to attach to theOUI and tow the OUI through the radiation scan beam. As the OUI is towedthrough the radiation beam, an image of the OUI is produced on theinspection computers housed within the trailer 15 showing theradiation-induced images of the articles and objects contained withinthe OUI.

Referring to FIG. 2, a rear elevation view of a preferred embodiment ofthe tug-vehicle 10, depicting the unloading of source of radiation 11using a lifting mechanism 12 is shown. As previously mentioned, in apreferred use of the system, the tug vehicle is separated from thetrailer and driven to an area where the source is to be positioned,preferably largely parallel to the trailer and separated from thetrailer by sufficient space to allow an OUI, such as a vehicle orcontainer, to pass.

To allow for the safe and rapid deployment of the radiation source 11, apreferred embodiment uses stabilizing feet 14 to increase the base ofthe tug vehicle 10 and off load the stress from the wheels, as thesource 11 is lifted off the tug-vehicle 10 using a suitable hydrauliclift 12 and brought down from the side for deployment. The radiationsource 11 may be put into position using any means known to one ofordinary skill in the art, such as a wheeled platform. The hydrauliclift 12 puts the source box 11 on a wheeled platform so that the sourcecan now be tugged and can be angularly rotated into a suitable position.

The source of radiation 11 includes radio-isotopic source, an X-ray tubeor any other source known in the art capable of producing beam flux andenergy sufficiently high to direct a beam to traverse the space throughan OUI to detectors at the other side. The choice of source type and itsintensity and energy depends upon the sensitivity of the detectors, theradiographic density of the cargo in the space between the source anddetectors, radiation safety considerations, and operationalrequirements, such as the inspection speed. One of ordinary skill in theart would appreciate how to select a radiation source type, dependingupon his or her inspection requirements. In one embodiment, where theOUI is a large sized container or car that highly attenuates the X-raybeam, the radiation could be from an X-ray tube operating at a voltagein substantial excess of 200 keV, and may operate in a region ofapproximately 4.5 MeV.

A further possibility for examining an OUI can be achieved by drivingthe radiation source 11 with respectively different radiation energiesor by using two detector systems, having varying sensitivities todiffering radiation energies. By comparing at least two congruentradiation images that were obtained with respectively differentradiation energies, it could be possible to discriminate articles havinglow and high ordering number. Organic materials, such as drugs andexplosives, can thus be better distinguished from other materials, forexample metals (weapons).

In another embodiment, the OUI can be examined with two radiationsources 11 having different energies. In one embodiment, the tworadiation sources 11 supply gamma radiation. In one embodiment, the twodifferent energies employed are ¹³⁷Cs and ⁶⁰Co, allowing the inspectionsystem to detect materials of both high and low atomic numbers. Anexample of a dual energy inspection system will be discussed in furtherdetail below, with respect to a single boom embodiment, wherein thedetector and radiation source are located on the same single boom. Itshould be noted here, however, that this embodiment is presented as anexample and is in no way limiting. For example, but not limited to suchexample, the dual energy inspection system of the present invention mayalso be used in a configuration wherein the radiation source box islocated on the tug vehicle and deployed for use on a wheeled base orplatform, as described with respect to FIGS. 1-12 below. In addition,the dual energy radiation inspection system of the present inventionemploys the same detector array to separately detect the attenuation ofthe differing energies impinging upon the OUI, which will also bedescribed in further detail below.

Referring back to FIG. 2, while the tug vehicle has been moved, with theradiation source, to a position for the deployment of the radiationsource, the inspection trailer is also being deployed. Now referring toFIG. 3, a side elevation view of the portable inspection trailer 15 isshown incorporating a boom 17 and a plurality of detectors 16 folded tothe side of the trailer 15. The detectors 16 are preferably in aformation that, when folded or stored permit the trailer 15 to safelytravel on public roadways. Additionally, the detectors 16 are preferablyintegrally formed to enable for stable, yet rapid deployment. Thedetectors may also be linear arrays that extend substantially parallelto the base of the trailer and, when deployed, extend substantiallyorthogonal to the base of the trailer.

In one embodiment, as shown in FIG. 4, the detectors comprise threesections 16 a, 16 b and 16 c that are capable of being folded, asearlier seen in FIG. 3, such that, when in a storage position, thedetectors recess into the side of the inspection trailer 15. By formingdetectors such that they can fold in a storage position, it is possibleto produce a compact trailer 15 that can safely, and legally, travelroadways. When unfolded during operation, the detectors 16 a, b and c,may assume a linear or an arched shape. In one embodiment the detectorsassume an approximate “C” shape, as seen in FIG. 4. The preferred “C”shape allows for a shorter total height of detectors in folded position,minimizes alignment problem because top and bottom sections 16 a, 16 care almost in the same line, provides a relatively smaller dose to alldetectors and are less prone to damage by the effective overall heightof the trailer 15. As shown, the detector sections 16 a, 16 b, and 16 care in alignment with a radiation source 11 that is powered through apower cable 25 attached to a boom 17. Within the area defined betweenthe detector sections 16 a, b, and c and the radiation source 11 is anOUI 20.

In order to facilitate push-button deployment and the dispensing away ofassembling tools or skill, the action of folding or unfolding of thedetectors 16 a, 16 b and 16 c is managed by a suitable hydraulic systemknown to a person of ordinary skill in the art.

FIGS. 6 and 7 show one embodiment of the inspection trailer 15,depicting the use of a typical hydraulic system 22 for deploying anexemplary array of linear-shaped detectors 21. During operation, thehydraulic mechanism 22, pushes the detectors 21 in a substantiallyvertical position while the stabilizing feet 25 and 26 are deployeddownwards so that the trailer 15 now partially rests on them instead ofjust on the wheels, thereby minimizing movement and providing stabilityto the trailer 15 during the scanning operation. A boom 23, is alsoshown in a rest position lying on the top of the trailer 20, and pivotedat one end around a vertical axis 24, such that the boom 23 can rise androtate orthogonally relative to the trailer 15 during deployment.

In one embodiment, as shown in FIG. 4, the detectors 16 remain folded toa side of the trailer 15 in an approximately vertical position so thatthe associated hydraulic mechanism is only used to unfold the foldedsections of the detector system 16. FIGS. 9 a and 9 b show an exemplaryhydraulic system 900 used to unfold the top detector panel 916 a. Thehydraulic system 900 comprises a reversible electrical motor 907 todrive a hydraulic pump 906 that in turn provides hydraulic fluid underpressure to a double acting hydraulic actuator 905 attached to trailer915. When the hydraulic actuator 905 is required to unfold the detector916 a, pressurized hydraulic fluid is pumped into chamber A, engagingpiston 908 to move slider ball 909 that in turn unfolds the detector 916a. Once the detector 916 a is unfolded through an acceptable angle 910the detector 916 a is securely latched in position using a mechanicallatch 920 such as a simple hook and peg system or any other latchingarrangement known to one of ordinary skill in the art. A similararrangement can be used to deploy the lower detector panel.

The detectors 16 may be formed by a stack of crystals that generateanalog signals when X-rays impinge upon them, with the signal strengthproportional to the amount of beam attenuation in the OUI. In oneembodiment, the X-ray beam detector arrangement consists of a lineararray of solid-state detectors of the crystal-diode type. A typicalarrangement uses cadmium tungstate scintillating crystals to absorb theX-rays transmitted through the OUI and to convert the absorbed X-raysinto photons of visible light. Crystals such as bismuth germinate,sodium iodide or other suitable crystals may be alternatively used asknown to a person of ordinary skill in the art. The crystals can bedirectly coupled to a suitable detector, such as a photodiode orphoto-multiplier. The detector photodiodes could be linearly arranged,which through unity-gain devices, provide advantages overphoto-multipliers in terms of operating range, linearity anddetector-to-detector matching. In another embodiment, an area detectoris used as an alternative to linear array detectors. Such an areadetector could be a scintillating strip, such as cesium iodide or othermaterials known in the art, viewed by a suitable camera or opticallycoupled to a charge-coupled device (CCD).

FIG. 8 shows a plan view of the inspection trailer 15, associated imageprocessing and control system 40 and an arrangement of detector system16 as seen from the top. As shown, the plane of the detector system 16represented by axis 35, is kept slightly skewed from the respective sideof the trailer 15 by an angle 36, such as 10°, so that the angle betweenthe trailer 15 and the path of the radiation beam 30 is substantially inexcess of 90°. At angles of about 90° and above, relative to scatterlocation and beam path 30, the magnitude of first order scatterradiation is quite low. In the present system, when radiation is firstemitted, the most likely scatter source is the detector system 16.Therefore the resulting relative angular position, between the axis 35and beam path 30 due to the skew angle of the detector plane 35 from thetrailer 15, helps in protecting driver 37 of the tug-vehicle 20 fromradiations scattered by the detector system 16.

The X-ray image processing and control system 40, in an exemplaryembodiment, comprises a computer and storage systems which records thedetector snapshots and software to merge them together to form an X-rayimage of the vehicle 20 which may further be plotted on a screen or onother media. The X-ray image is viewed or automatically analyzed by OUIacquisition system such as a CRT or monitor that displays the X-rayimage of the vehicle 20 to an operator/analyst. Alternatively, the OUIacquisition systems may be a database of X-ray images of desiredtargets, such as automobiles, bricks or other shapes that can becompared with features in the image. As a result of this imaging, onlyarticles that were not contained in the reference image of the containeror vehicle 20 are selectively displayed to an operator/analyst. Thismakes it easier to locate articles that do not correspond to a referencecondition of the container or vehicle 21, and then to conduct a physicalinspection of those articles. Also, for high-resolution applications,the electronics used to read out the detector signals may typicallyfeature auto-zeroed, double-correlated sampling to achieve ultra-stablezero drift and low-offset-noise data acquisition. Automatic gain rangingmay be used to accommodate the wide attenuation ranges that can beencountered with large containers and vehicles.

Referring now to FIG. 10, during deployment the inspection trailer istransported 1005 to the operation site and towed 1010 in position by thetug-vehicle. The trailer is advantageously positioned proximate to acargo loading area so that the laden cargo containers can pass throughthe source-trailer system without disrupting port activities. One suchpreferable place for positioning the trailer could be an exit point of aport. Another aspect that may influence the decision of positioning thetrailer could be the availability of a large enough area, called the“exclusion zone”, around the scanner system. The exclusion zone is anarea around the scanner in which general public are not authorized toenter due to the possibility of their getting exposed to doses ofradiations scattered during the scanning process. The exclusion area isdependent upon the magnitude of current setting the intensity of theradiation source.

After positioning the trailer suitably, the tug-vehicle is preferablydetached 1015 from the trailer. Next the tug vehicle is moved 1020 to anarea proximate to and preferably parallel from the inspection trailer inorder to unload and position the source of radiation. The source ofradiation is then pulled 1025, or lowered, out of the tug-vehicle, usinga hydraulic lift, and lowered down to the ground to be deployedlaterally opposite to the side of the trailer supporting the detectors.The boom is also rotated 1030 substantially orthogonally from its restposition in order to deploy 1030 control cable to provide power andcontrol signals to the source. The electrical power generator, housed inthe trailer, is now turned on 1035 to provide power to the electricaldevices in the system.

While the generator is deployed described above, the detectors areunfolded 1045. The detectors may be positioned in a variety of ways, asearlier described, including a linear or, using a suitable hydraulicmechanism, in an approximate “C” shape. Shown in FIG. 11 is a processflow diagram of the detector deployment process. Stabilizing feet arefirst deployed 1105 to provide stability to the trailer as it deploysthe detector structure. One of ordinary skill in the art wouldappreciate that the objective of deploying stabilizing feet is to widenthe trailer support base and distribute weight to increase stability andlessen the likelihood of tipping. Other mechanisms could be used tostabilize the trailer structure, including, for example, a hydraulicjack that lifts the trailer up so that the trailer now rests on asupport platform instead of on the wheels; hydraulic brakes that areengaged once the trailer has been suitably positioned such that thebrakes cusp the trailer wheels preventing any movement of the wheels; orsimply a pair of wheel-stops that can be manually placed in front and atthe rear of front and rear wheels respectively preventing anytranslational motion of the wheels.

Once the trailer is stable, the reversible electric motor of thedetector hydraulic system is turned on 1110. The motor starts 1115 thehydraulic pump that fills 1120 the hydraulic actuator with pressurizedhydraulic fluid. This moves 1125 the hydraulic piston, attached to thedetector through a slider ball, causing the detector to unfold 1130upwards. After unfolding the detector panel to a suitable position, thedetector panel is latched 1135 in order to hold it in the requiredunfolded position. A similar process is carried out to unfold the bottompanel of the detector system.

Once the radiation source box is placed opposite to the detector arrayand the array box is fully deployed, alignment 1040 steps are carriedout comprising of: adjusting the vertical height of the radiation sourcebox using leveling mechanisms such as leveling screws or any otherleveling means known to a person of ordinary skill in the art; andalignment of the radiation beam with respect to the detectors.

FIG. 12 is an exemplary embodiment of the radiation source box 11,showing leveling screws 5, 6, 7 and 8 that can be turned to manipulatethe vertical height of the source box 11 and an array of laser pointers9 built into the collimator 10 to facilitate proper alignment of theradiation beam 12 with the detectors. In one embodiment, opticaltriangulation method is used for aligning the plane of the radiationbeam with a predefined “zero” or “idealized centerline” of the detectorsystem. Such optical triangulation techniques, as known to a person ofordinary skill in the art, use a source of light such as a laser pointerto define the radiation beam path. These laser pointers are directed toimpinge on a predefined “zero” of the detectors. The “zero” of thedetectors maybe a spot representing the centroid of the detector systemor an idealized centerline representing a spatial x-y locus of an idealfan beam plane intersecting the plane of the detectors substantiallyorthogonally. In one arrangement, the spatial position of the laserpointers impinging on the detectors is sensed by an array ofphoto-electric diodes of the detector system that send the correspondingposition signals to a computer housed within the trailer. The computercompares the spatial position of the laser pointers with a predefined“zero” of the detector system and sends correction control signals tothe source box through the control cable (attached to the boom) foradjustments till the laser pointers are reasonably lined-up with thedetector system

Depending on conditions, other system elements may be deployed to enablethe screening process. Such elements may include surveillance systemssuch as the closed-circuit television (CCTV) to monitor area around thescanner to control the exclusion zone, a lighting system and a wirelessnetwork. The lighting system may be required to facilitate nightoperation. In a preferred embodiment the analysis of the scanned imagesof an OUI are done by an analyst seated inside the inspection trailer.However, in another embodiment a separate command center mayalternatively or additionally be located away from the scanner,preferably outside the exclusion zone, where a similar analysis ofscanned images may be done. In such an arrangement wireless networks mayadditionally be needed to transfer data from the scanner system to thecommand center.

After deploying the system as described above, an operator may undertakethe following procedure to examine an OUI using the present invention.As used in this description, an OUI is any receptacle for the storage ortransportation of goods, and includes freight pallets as well asvehicles, whether motorized or drawn, such as automobiles, cabs andtruck-trailers, railroad cars or ship-borne containers and furtherincludes the structures and components of the receptacle.

In an alternate embodiment, the radiation source box comprises at leastone radiation source having translational movement, allowing forimproved safety and efficiency. The movable (or translatable) radiationsource is employed to provide both an “active” and “stowed” position ofthe radiation source, where, when in the “active” position, the movableradiation source is aligned with the beam port aperture of the sourcebox. In one embodiment, the beam port aperture is greater than 80degrees to allow for the radiation path to radiate upon the entiredetector arrangement on the boom. When in the “stowed” position, theradiation source is offset from the beam port aperture of the source boxby an optimal distance. In one embodiment, the optimal offset distanceis 3 inches. In addition, in the “stowed” position, in one embodiment,the radiation source is encapsulated inside a shield and thus, at a safeposition. In one embodiment, the radiation source is encapsulated in atungsten and lead shield. Preferably, the tungsten and lead shield is ofadequate shielding capability to contain the gamma radiation source andensure that exposure in a closed position is below NRC safe levels.

It should be noted herein that the direction of movement or translationof the radiation source is not limited. Thus, the radiation source canbe moved horizontally, vertically, or in any other direction asnecessary for operation.

While FIGS. 12 a-12 s are described in general, it should be noted thatthe radiation source box of the present invention can be employed inseveral different configurations. As described above, in one embodiment,the radiation source box is located on the trailer, but not permanentlyaffixed to the boom. In this embodiment, the radiation source box istowed to the deployment site and positioned on a movable platform foruse. This embodiment is described in detail above with respect to FIGS.1-12 and will not be repeated herein. Also as described above withrespect to FIGS. 13-26 below, the radiation source box is, in oneembodiment, located on the distal end of the single structural boomfixedly connected to the trailer.

FIG. 12 a is a block diagram of one embodiment of the radiation sourcesystem of the present invention, including associated peripheraldevices. In one embodiment, radiation source system 1200 a comprisescomputing device 1201 a, interface card 1202 a, driver 1203 a, and aradiation source box 1204 a which further comprises a radiation sourceactuator 1205 a and a radiation source 1206 a.

Computing device 1201 a processes the input received by the operator viaany suitable input device (not shown) operably connected to computingdevice 1201 a. The operator input activates the radiation sourceactuator 1205 a connected to the computing device 1201 a via interfacecard 1202 a and driver 1203 a.

The operator inputs information into the software system via keyboard,mouse, stylus, joystick, touch pad, trackball or any other suitableinput device for subsequent data processing, as are well-known to thoseof ordinary skill in the art. In one embodiment, the operator inputinformation is a voltage value. In one embodiment, the voltage valuesare transmitted to the radiation source system 1200 a remotely via anywirelessly enabled computing device.

In another embodiment, radiation source system 1200 a is operated viaremote control. In one embodiment, the remote control is used to controlpower to the radiation source system. In one embodiment, the remotecontrol is used to control the scanning operation of the radiationsource system. It should be noted herein that the remote control used topower and operate the radiation source system may also be used toperform other functions with respect to the overall system. Thesefunctions include, but are not limited to controlling boom movement,performing image processing functions, and allowing for operator inputfor decision-making.

The computing device 1201 a transmits the voltage level corresponding tothe operator input to the interface card 1202 a, which further transmitsit to the driver 1203 a connected to the radiation source actuator 1205a. Radiation source actuator 1205 a then moves the radiation source in aposition for scanning based on the values received by the driver 1203 a.Computing device 1201 a is, in one embodiment, a microprocessor basedcomputer system and operates under the control of a software system.

FIG. 12 b is one embodiment of an outer enclosure of the radiationsource box of the present invention, further illustrating safetyindicators. In one embodiment, outer enclosure 1207 b comprises at leastone safety indicator and a top cover 1211 b. The safety indicator ispreferably used to alert inspection personnel and other individualspresent at the inspection site that radiation is emanating from thesource and is in an active position, thus actively monitoring theradiation exclusion zone. In one embodiment, the safety indicator is alight 1208 b that is movably connected to outer enclosure 1207 b. Thelight 1208 b preferably flashes red to indicate caution and alsopreferably rotates when the radiation source is in a scanning mode andgamma rays are present in the scan zone. In another embodiment, thesafety indicator is a flag 1209 b, that further comprises an electronicmechanism that is activated by the radiation source box. The flag 1209 bis preferably red to indicate caution. Flag 1209 b is raised in an “up”position when the radiation source is active and in an open position andis lowered when the radiation source is inactive and in a closedposition. In yet another embodiment, the safety indicator is a buzzer1210 b. The buzzer 1210 b preferably sounds an alarm when the radiationsource is active. In another embodiment, the radiation source box of thepresent invention comprises at least one safety indicator. In anotherembodiment, the radiation source box of the present invention comprisesat least two safety indicators. In another embodiment, the radiationsource box of the present invention comprises three safety indicators.The operational characteristics of the various embodiments of the safetyindicator are described in greater detail below.

FIG. 12 c is an illustration of one embodiment of the radiation sourcebox of the present invention, mounted on a truck boom. The single boomstructure 1212 c, described in further detail below, permits theradiation source box 1213 c to rigidly align with the detector array,permitting the unit to operate with a narrower beam width and a lowerradiation level. In one embodiment, radiation source box 1213 c ispositioned at the base of the single boom via a connecting structure1214 c. In addition, positioning radiation source box 1213 c at the baseof boom 1212 c enables a larger field of view relative to conventionalsystems having the source on the vehicle. Radiation source box 1213 ccan preferably be lowered to a height as low as six inches off theground, as shown in FIG. 12 c as 1215 c.

FIG. 12 d is an illustration of the internal components of the radiationsource box of the present invention. As shown in FIG. 12 d, radiationsource box 1216 d further comprises a source collimator 1217 d, shieldedcask 1218 d, flag cable 1219 d, and cylindrical cover 1220 d. In oneembodiment, radiation source box 1216 d further comprises a movable ortranslatable radiation source (not shown), which is housed in shieldedcask 1218 d. Cylindrical cover 1220 d is preferably used to cover orencapsulate the actuator (not shown), but described in greater detailwith respect to FIGS. 12 f and 12 g. In one embodiment, the sourcecollimator 1217 d permits the fan beam to emerge from shielded cask 1218d, when the radiation source is in an active and open position. Flagcable 1219 d is operably connected to both flag 1221 d and the actuator(not shown) so that it can be used to indicate the position of thesource pellet.

FIG. 12 e is a detailed illustration of the radiation source box of thepresent invention without the cylindrical housing cover shown in FIG. 12d. In one embodiment, safety spring 1222 e is located underneath thecylindrical housing cover (not shown). Safety spring 1222 e ensures afail-safe closure of the radiation source when the power supply is cutoff. In one embodiment, audio alarm 1223 e is also present underneaththe cylindrical housing cover (not shown). Audio alarm 1223 e activatesan auditory “beeping” alarm for the duration that the source is in anunsafe, active or open position.

In one embodiment of the present invention, the radiation sourceactuator comprises an electric solenoid. The electric solenoid convertselectrical energy from the inspection system into a translational energythat moves the radiation source to an operational/active position to astowed position and vice versa. FIG. 12 f is an illustration of anelectric solenoid for use with one embodiment of the radiation sourcebox of the present invention. The electronic solenoid 1230 f comprisesof a coil 1224 f, armature 1225 f, spring 1226 f, stem 1227 f, andcontrol plate 1228 f. The coil 1224 f is connected to the power supply1229 f, which is preferably from the inspection system in which theradiation source box is employed. Spring 1226 f, in one embodiment,rests on the armature 1225 f and enables it to move vertically insidethe coil 1224 f and further transmits its motion through the stem 1227 fto the control plate 1228 f.

In operation of the electric solenoid, a magnetic field is formed aroundcoil 1224 f when current flows through it. The magnetic field attractsarmature 1225 f toward the center of coil 1224 f. The downward movementof armature 1225 f collapses spring 1226 f, and results in the controlplate 1228 f moving downward. In one embodiment of the presentinvention, the downward movement of control plate 1228 f aligns theradiation source and aperture for scanning operation. When the currentstops flowing, spring 1226 f is expanded to its original shape, thuspushing control plate 1228 f upwards. This results in the shielding ofthe radiation source inside the casing.

In an alternate embodiment of the present invention the radiation sourcebox actuator employs a pneumatic solenoid. The pneumatic solenoidconverts highly compressed air into a translational energy therebymoving the radiation source box to an operating position from the restposition and vice versa. FIG. 12 g is an illustration of a pneumaticsolenoid for use with one embodiment of the radiation source box of thepresent invention. Pneumatic solenoid 1231 g comprises a diaphragm 1232g, mechanical stop 1233 g, air vent 1234 g, spring 1235 g, stem 1236 gand control plate 1237 g. Diaphragm 1232 g separates the solenoidhousing into two air chambers, upper chamber 1238 g and lower chamber1239 g. Upper chamber 1238 g receives the air supply from air vent 1234g in the housing. Lower chamber 1239 g includes a spring 1235 g thatforces diaphragm 1232 g up against mechanical stop 1233 g in lowerchamber 1239 g. The position of control plate 1237 g is controlled byvarying air pressure in upper chamber 1238 g.

In operation, with no supply of air, spring 1235 g of pneumatic solenoid1231 g enables diaphragm 1232 g to move up against mechanical stop 1233g and enables the downward movement of the control plate 1237 g. Thedownward movement of the control plate 1237 g, in this embodiment,aligns the radiation source and aperture for scanning operation. With anincrease in air supply, diaphragm 1232 g will move upward and compressspring 1235 g, thus pushing control plate 1237 g upwards and resultingin shielding the radiation source inside the casing.

As described in greater detail below with respect to FIGS. 12 h and 12i, the actuator is thus employed to move the radiation source into anoperable position by positioning the radiation source directly in frontof the aperture when the radiation source is powered on. Conversely,when the radiation source is powered off, the radiation source is offsetby at least three inches away from the aperture, such that it is in a“closed” and inactive position.

FIG. 12 h is a cut-away illustration of one embodiment of an actuatormechanism as used in the radiation source box of the present invention.Referring now to FIG. 12 h, actuator mechanism 1240 h comprises firstspring 1241 h and second spring 1242 h. In one embodiment, first spring1241 h and second spring 1242 h are safety springs and are used toensure fail-safe closure of the source when not in operation. Springs1241 h and 1242 h are coiled about first and second actuator rods 1243 hand 1244 h, respectively. Power applied to the solenoid 1245 h,described in detail above, results in the translatable movement ofactuator rods 1243 h, 1244 h. In one embodiment, the actuator rods aremoved a distance of three inches, via the solenoid, between a firstdampener 1246 h and a second dampener 1247 h. The hydraulic dampenersare employed to dampen the “opening” and “closing” motion of theactuator. During the “opening” motion of the actuator, actuator rods1243 h, 1244 h align the source, in front of the aperture and thus, withthe object under inspection, for scanning. During the “closing” motionof the actuator, actuator rods 1243 h, 1244 h move the source away fromthe aperture and thus in a “safe” position.

FIG. 12 i depicts one embodiment of a hinged door for use with theradiation source box of the present invention, which when opened,provides access to the actuator. In one embodiment, radiation source box1250 i further comprises hinged door 1251 i. Hinged door 1251 i, whenopened, provides access to the actuator (not shown). In providing accessto the actuator, in one embodiment, the operator is able to insert alocking rod (not shown) to lock the radiation source system to avoid anypossible movement and subsequent leakage of the radioactive sources.When locked, the radiation source system of the present invention caneasily and safely be moved from one location to another.

FIG. 12 j is a flowchart showing the operational steps of the radiationsource box system of the present invention. To begin the scan operation,the operator of the inspection system of the present invention deploysthe inspection system, in step 1260 j, at the inspection site. Thedeployment of the single boom inspection system of the present inventionis described in great detail below and will not be repeated herein. Theobject or vehicle under inspection is then moved, in step 1262 j, to theinspection site. After deploying the boom and inspection system, theoperator initiates, in step 1264 j, a “Start Scan” operation.Preferably, the control panel, also described below, is used to initiatethe scan.

In another embodiment, the scan may be initiated by a sensor that isemployed to determine when a target object is positioned between theradiation source and the detector array. The sensor, upon beingactivated by the movement of a target object, transmits a signal toactivate said radiation source. Although it is possible to use such asensor, the present invention is described with respect to anoperator-initiated scan and thus, the use of a sensor will not bedescribed in detail herein.

The radiation source actuator of the present invention is subsequentlyactivated, in step 1266 j. Upon actuation, the radiation source ismoved, in step 1268 j, by a suitable distance to align the radiationbeam in the direct path of the aperture for scanning. In one embodiment,three inches is a suitable distance. Thus, in step 1270 j, the radiationsource is aligned with the aperture. During scanning, the radiation beamis in line with the aperture and thus “active” and “open”. In step 1272j, the radiation beam passes through the aperture and the object orvehicle under inspection is scanned. When the scanning operation iscomplete, the operator initiates, in step 1274 j, a “Stop Scan”operation. This “Stop Scan” operation, in step 1276 j, returns theradiation source actuator back a suitable distance so that the radiationsource is in an “inactive”, “closed” safe position. In one embodiment, asuitable distance is three inches. The radiation source box is thenshielded, in step 1278 j, after being placed in a safe position.

In one embodiment, the radiation source box of the present inventionfurther comprises a source transport assembly which allows for theradiation source box to be mounted on any mobile vehicle inspectionsystem, independent of the type of truck used to house or tow thesystem.

FIG. 12 k is an illustration of one embodiment of the source transportassembly for transporting and installing the radiation source box on theboom of the inspection system in one embodiment of the presentinvention. In one embodiment, the source transport assembly bracketcomprises frame structure 1281 k which is used to house the radiationsource box 1286 k. Frame structure 1281 k is preferably metallic. In oneembodiment, frame structure 1281 k further comprises base member 1282 k,angular frame member 1283 k, and fastener assembly 1284 k. Fastenerassembly 1284 k, in one embodiment, comprises various nuts and bolts, asare known to those of ordinary skill in the art. In one embodiment,radiation source box 1286 k rests on base member 1282 k of framestructure. In addition, in one embodiment, radiation source box 1286 kis fixed to angular frame member 1283 k via fastener assembly 1284 k. Oneach top corner of frame structure 1281 k, metallic loops 1285 k areprovided. In one embodiment of the present invention four ropes are tiedto each loop 1285 k for lifting the entire assembly from the ground andplacing it on the boom via crane or any other suitable lifting device.

In another embodiment, source transport assembly bracket is re-usableand can be employed to mount the source and transfer the source from thebracket to the truck boom with ease and minimal handling.

FIG. 12 m is an illustration of another embodiment of a source transportassembly bracket for mounting the radiation source box of the presentinvention for subsequent transporting and installing the radiationsource box on the boom of the scanning system of the present invention.As shown in FIG. 12 m, the source transport bracket 1286 m furthercomprises base 1288 m. Optionally, a rubber bumper can be mounted onbase 1288 m of the transport bracket to provide a cushion under thesource for vibration tolerance. The source and actuator are preferablyshielded from vibration to protect the components. Source transportassembly further comprises leveling feet 1289 m. In addition, the sourcetransport assembly further comprises mounting holes 1290 m for securinga shipment crate, as explained in greater detail below.

FIG. 12 n is an illustration of the source transport bracket assemblyshown in FIG. 12 m, with the radiation source box installed. Radiationsource box 1291 n is securely connected to the source transport assemblyvia fastener assembly 1292 n. In one embodiment, the radiation sourcebox 1291 n is securely connected via nuts and bolts, as are well-knownto those or ordinary skill in the art. FIG. 12 o is a front-viewillustration of the source transport assembly 1290 o shown in FIG. 12 m,with the radiation source box installed.

FIG. 12 p is an illustration of the source transport assembly shown inFIG. 12 m, with the radiation source box installed and the boom sourcearm in position for transfer. In one embodiment, boom arm 1293 p ispositioned in front of the radiation source box 1294 p so that it can beeasily transferred, with minimal disruption to the radiation sourcesystem, from the bracket to the truck boom. In addition, leveling feet1295 p are used to position the source in an optimal position fortransfer to the truck boom.

In another embodiment, the source transport assembly bracket isre-usable and can be employed to transport the radiation source to theinspection site with ease and minimal handling. In one embodiment, ashipment crate cover and base is employed to help transport theradiation source box and bracket assembly.

FIG. 12 q is a schematic illustration of the source transport assemblywith the radiation source box installed, with a shipment crate cover. Inone embodiment, the shipment crate cover is a five-sided crate that isslid over the transport bracket and secured using mounting holes 1296 qon the bottom of the bracket. In one embodiment, bolts are used tofasten and secure the shipment crate over the radiation source box andtransport bracket. FIG. 12 r is another illustration of the sourcetransport assembly with the radiation source box installed, with ashipment crate cover. In one embodiment, radiation source box andtransport assembly are brought proximate to boom arm (not shown) via aforklift. The forklift can access the radiation source box and transportassembly bracket via forklift cut-outs 1297 r.

FIG. 12 s is an illustration of the base of the shipment crate used totransport the radiation source box and bracket assembly. Base 1298 sfurther comprises casters 1299 s, which are used for locally moving andaligning the radiation source box, transport bracket and shipment crateat the truck. In one embodiment, re-usable straps (with ratchets) areused to secure the top cover of the shipment crate to the base.

Thus, in one embodiment, to mount and transport the radiation source boxand actuator mechanism for use in the scanning system of the presentinvention, the radiation source box is first mounted on the sourcetransport bracket assembly. The shipment crate cover is then placed onthe bracket assembly, when is then lifted onto the shipment base. Theprotected radiation source box is then transported to the inspectionsite. Once at the inspection site, the protected radiation source box isforklifted to the inspection area. The protected radiation source box isthen positioned proximate to the truck boom, where the shipment cover isremoved. The casters at the base are used to locally position theradiation source box and bracket assembly for transfer to the boom. Inaddition, leveling feet are used to stabilize and position the radiationsource box and bracket assembly for transfer to the boom. The radiationsource box is then transferred from the bracket assembly to the boom.The source bracket assembly and shipment cover and base are reusable.

Referring back to FIG. 5, a side elevation view of the system of oneembodiment of the invention during operation is shown. The OUI in thisillustration is a vehicle 20 that is being towed between the source 11and detectors 16 by the tug-vehicle 10. In a preferred arrangement thetug-vehicle 10 is the same vehicle that was earlier used to transportthe inspection trailer 15 to the site. Thus the tug-vehicle 10 servesthe twin purpose of not only transporting the inspection trailer 15 butalso to tow an OUI, such as vehicle 20, during the scanning process toprovide a relative motion between an OUI and the source 11/detector 16system. The mechanism used to attach the tug-vehicle 10 to the trailer15 and then to an OUI during operation may be different. For example,one or more wheel catchers 22 that cups one or more wheels of an OUI,thereby allowing the tug vehicle 10 to pull the OUI by dragging thewheel catcher 22, may be used to tow the inspected vehicle 20.Similarly, other attachment mechanisms may alternatively be used, aswould be known to persons ordinarily skilled in the art.

During the scanning operation, the source 11 and detectors 16 remainstationary and aligned with respect to each other while the OUI, whichis a vehicle 20 in this case, is made to move. In a preferredembodiment, the motion of the vehicle 20 is kept steady and at aconstant velocity such as at or around 2 km/hr. Since, irregularities inthe motion of the vehicle 20 may result in distortions in the scannedimage, the motion is preferably made as regular, even and constant asfeasible using known control systems such as by engaging the tug-vehicle10 in “auto speed” mode. In alternate embodiments, to scan at varyingspeeds depending on the speed of the tug-vehicle 10, irregularities ofmotion are measured and the radiographic image is correspondinglycorrected. To accomplish this, a telemetry mechanism may be used torelay the speed of the tug-vehicle 10 to the inspection trailer 15. Forexample, one or more motion encoders can be affixed to one wheel of thetug-vehicle 10. An encoder measures the rotational velocity of the wheeland transmits a corresponding electrical signal to the imaging system'scomputer housed within the inspection trailer 15. If there is a changein speed, the computer automatically includes a correspondingcompensation in the timing of the detector signals for that location,thereby eliminating image distortions induced due to non-uniform motionof the tug-vehicle 10.

Start-sensors, not shown, are strategically placed to allow an imagingand control system, located within the inspection trailer 15, todetermine that the tug-vehicle 10 has passed the area of beam and thevehicle 20 to be inspected is about to enter the X-ray beam position 30.Thus, as soon as the vehicle 20 to be inspected trips the start-sensors,the radiation source 11 is activated to emit a substantially planarfan-shaped or conical beam 30 (for the duration of the pass) that issuitably collimated for sharpness and made to irradiate substantiallyperpendicular to the path of the vehicle 20.

Since the source 11 and detector 16 remain stationary during thescanning process, collimation can be adjusted to an advantageous minimumsuch that the fan beam emerging out of the collimator just covers thedetectors 16. Apart from using a collimator at the source of radiation,in an alternate embodiment, another collimator arrangement can beadditionally provided integral to the detector system 16 so that thewidth of the fan beam finally striking the detectors 16 may be furtherchanged. As known in the art, X-ray scanning operates on the principlethat, as X-rays pass through objects, some get stopped, some passthrough, and some get deflected owing to a number of different physicsphenomena that are indicative of the nature of the material beingscanned. In particular, scattering occurs when the original X-ray hitsan object and is then deflected from its original path through an angle.These scatter radiations are non-directional and proportional to thetotal energy delivered in beam path. A narrowly collimated beam willkeep the overall radiation dose minimal and therefore also reduce theamount of scatter radiation in the area surrounding the scanner. This,in one arrangement, is achieved by using an adjustable collimator with along snout.

Also, the fan angle of the fan beam 30 is wide enough so that theradiation from the source 11 completely covers the cross section of thevehicle 20 from the side and the radiation is incident on theapproximately “C”-shaped radiation detectors 16. It would also bepossible to make the fan angles of the source 11 smaller than would benecessary to encompass the entire cross-section of the articles beinginspected, in which case the source 11 could be mounted so as to bepivotable around an axis that is essentially parallel to the directionof motion of the vehicle 20. Thus, by pivoting the source 11, theentirety of the cross section of the vehicle 20 can be penetrated by theradiation.

At any point in time when the source 11 is on, the detectors 16 aresnapshots of the radiation beam attenuation in the vehicle 20 for aparticular “slice” of the vehicle 20 under inspection. Each slice is abeam density measurement, where the density depends upon beamattenuation through the vehicle 20. The radiation detectors 16 convertthe lateral radiation profile of the vehicle 20 into electrical signalsthat are processed in an image processing system, housed in theinspection trailer 15, while the vehicle 20 is being conducted past thesource 11 and the radiation detector 16.

In a second embodiment, the present invention is directed towards arelocatable cargo inspection system that employs a single boom attachedto a truck that is capable of receiving and deploying the boom. The boomcomprises a plurality of radiation detectors and a source. The boom ispreferably installed in the rear of the truck to minimize radiationdosage to the driver and is capable of being folded into the truck andfolded out, thus forming an inverted “L” on either the driver orpassenger side.

The single boom structure permits the source, positioned at the base ofthe connecting structure, to rigidly align with the detector array, alsopermitting the unit to operate with a narrower beam width and a lowerradiation level. In addition, the position of the source at the base ofthe connecting structure enables a larger field of view relative toconventional systems having the source on the vehicle. The sourcepreferably extends to a height as low as six inches off the ground.Reference will now be made in detail to specific embodiments of theinvention. While the invention will be described in conjunction withspecific embodiments, it is not intended to limit the invention to oneembodiment.

Referring to FIG. 13, the schematic representation of an exemplaryembodiment of the integrated single boom cargo scanning system of thepresent invention is depicted. The self-contained inspection system 1300of the present invention comprises, in a preferred embodiment, aninspection module in the form of a rig/tractor trailer 1301, capable ofbeing driven to its intended operating site. The vehicular portion ofthe system and the inspection module portion of the system areintegrated into a single mobile structure. The integrated modular mobilestructure serves as a support and carrier structure for at least onesource of electromagnetic radiation; and a possible radiation shieldplate on the back of the driver cabin of the vehicle, used to protectthe driver from first order scatter radiation.

The inspection or scanning module 1300 is custom-built as an integratedmobile trailer 1301 and can provide support for a single boom 1302 todeploy a power cable (not shown) to at least one source of radiation1304 during operation. In one embodiment, the at least one source ofradiation is capable of emitting radiation of at least one energy. Inone embodiment, the at least one source of radiation is capable ofemitting radiation in two different energies. In another embodiment, theinspection or scanning module 1300 can provide support for two sourcesof radiation 1304. The operational characteristics of using two sourcesof radiation 1304 having two different energies are discussed in greaterdetail below with respect to FIGS. 27-29.

Now referring back to FIG. 13, boom 1302 additionally houses an array ofdetectors 1303. In a preferred embodiment, boom 1302 is attached totrailer 1301, capable of receiving and deploying the boom. Boom 1302 ispreferably installed and located in the back of trailer 1301 to minimizeradiation dosage to driver in trailer cab 1305. Trailer 1301 also housesan operator/analyst cabin including computer and imaging equipment alongwith associated power supplies, air conditioning and power generatingequipment (not shown) in accordance with the understanding of a personof ordinary skill in the art of X-ray generation. Depending onconditions, other system elements may be deployed to enable thescreening process. Such elements may include surveillance systems suchas the closed-circuit television (CCTV) to monitor area around thescanner to control the exclusion zone, a lighting system and a wirelessnetwork. The lighting system may be required to facilitate nightoperation. In a preferred embodiment the analysis of the scanned imagesof an OUI are done by an analyst seated inside the inspection trailer.However, in another embodiment a separate command center mayalternatively or additionally be located away from the scanner,preferably outside the exclusion zone, where a similar analysis ofscanned images may be done. In such an arrangement wireless networks mayadditionally be needed to transfer data from the scanner system to thecommand center. In addition, boom 1302 is capable of being folded intotrailer 1301 in a “stowed” position or folded out from trailer 1301 in a“deployed” position, on either the driver or passenger side.

The radiation source box 1304 is located on the same single boom 1302 asthe detection system 1303. Thus, while source box 1304 is locatedopposite the detector system 1303 at a distance that is suitable toallow Object under Inspection (“OUI”) to pass in the area 1306 betweenthe source 1304 and detector array 1303 during the scanning process, itis located on the same boom 1302 to eliminate the need for alignment. Inone embodiment, the radiation source is an X-ray generator. In yetanother embodiment, the radiation source is a linear accelerator(LINAC). If the X-ray generator or LINAC is mounted on the same singleboom as the detector arrays, the need for sophisticated alignmentsystems each time the system is deployed is eliminated. Thus, theradiation source and detectors are substantially permanently aligned onthe same single boom. The feature also allows for scanning at variousdegrees of offset, again without the need to realign the LINAC or X-raygenerator and detectors.

An OUI could be any type of object, including cars, trucks, vans, cargocontainers, mobile pallets with cargo, or any other type of cargoobject. During the scanning process, the OUI remains in the areademarcated by the deployed boom 1306 as a fixed piece of cargo while theself-contained inspection rig/tractor trailer 1300 moves over the OUI.Alternatively, the self-contained inspection rig/tractor trailer 1300can remain in place while a piece of cargo is driven, moved, dragged,tagged, and/or lifted through the scanning region 1306. As theself-contained inspection trailer 1300 is moved over OUI, an image ofthe OUI is produced on the inspection computers housed within thetrailer showing the radiation-induced images of the articles and objectscontained within the OUI (not shown). Therefore, in a preferredembodiment, the system is designed such that the self-containedinspection trailer moves over the stationary object (OUI).

The source of radiation includes radio-isotopic source, an X-ray tube,LINAC or any other source known in the art capable of producing beamflux and energy sufficiently high to direct a beam to traverse the spacethrough an OUI to detectors at the other side. The choice of source typeand its intensity and energy depends upon the sensitivity of thedetectors, the radiographic density of the cargo in the space betweenthe source and detectors, radiation safety considerations, andoperational requirements, such as the inspection speed. The system ofthe present invention could employ source-based systems, for example,cobalt-60 or cesium-137 and further employ the required photomultipliertubes (PMT) as detectors. If a linear accelerator (LINAC) is optionallyemployed, then photodiodes and crystals are used in the detector. One ofordinary skill in the art would appreciate how to select a radiationsource type, depending upon his or her inspection requirements.

In one embodiment, where OUI is a large sized container or car thathighly attenuates the X-ray beam, the radiation could be from an X-raytube operating at a voltage in substantial excess of 200 keV, and mayoperate in varying regions, including 450 keV, 3 MeV, 4.5 MeV, and even,but not limited to 6 MeV.

In one embodiment, the present invention employs dual source-basedsystems and further employs the required photomultiplier tubes asdetectors. In one embodiment, ⁶⁰Co is used as a first gamma ray sourceand has a high specific activity of the order of 11.1 TBq (300 Ci) and alinear dimension of the active area of 6 mm. In one embodiment, thesecond gamma ray source is a 1.0, 1.6 or 2.0 Curie shutteredmono-energetic source of ¹³⁷Cs gamma rays, having a 662 keV energy.

In another embodiment, a nearly mono-energetic ⁶⁰Co gamma ray source isused, which is capable of emitting photons at two distinct energylevels, more specifically, 1170 an 1339 KeV. In one embodiment, thegamma rays emitted from the 60Co source are collimated by their slits toform a thin fan-shaped beam with a horizontal field angle of 0.1° and avertical field angle of 65°.

FIGS. 14 and 15 depict a side view illustration and top viewillustration, respectively, of one embodiment of the vehicle of thepresent invention in a folded, or “stowed” position. In this position,the single boom 1401, 1501 detector arrays 1402, 1502 and radiationsource 1403 fold onto the flatbed 1404, 1504 of the vehicle/trailer1405, 1505. Thus, the detector arrays 1402, 1502 and radiation source1403 are preferably positioned in a manner, such that when folded orstored, permit trailer 1405, 1505 to travel safely on public roadways.Additionally, the detectors are preferably integrally formed to enablefor stable, yet rapid deployment. The detectors may also optionally belinear arrays that extend substantially parallel to the base of thetrailer and, when deployed, extend substantially orthogonal to the baseof the trailer.

Referring to FIG. 16, a side perspective view of the single boom cargoscanning system of the present invention in a stowed or “folded”position is depicted. In one embodiment, trailer 1601 comprises chassis1602, having a front face 1603, a rear end 1604, and sides 1605. Trailer1601 also comprises a trailer (driver's) cab 1610 and a single boom1611. In a preferred position, boom 1611 extends centrally above chassis1602 from a point (shown as 1612) approximately above rear axle 1607,thus allowing it to rotate in the desired directions. Boom 1611 has aproximal end attached to the vehicle and a distal end physicallyattached to the radiation source. Boom 1611 preferably consists of ahollow cylindrical main body 1613, a connecting structure 1614, an outerarm 1615, and a telescopic arm 1616. Outer arm 1615 protrudes from theconnecting structure 1614 to preferably form an L-shaped structure. Bothouter arm 1615 and connecting structure 1614 comprise detector panels(not shown).

Outer arm 1615 is further connected to telescopic arm 1616. Hydrauliccylinders or actuators (not shown) are provided for the turning movementof boom 1611, outer arm 1615 and telescopic arm 1616. In order tofacilitate push-button deployment and the dispensing away of assemblingtools or skill, the action of folding or unfolding of the outer arm 1615containing the detector array is enabled by a suitable hydraulic systemknown to a person of ordinary skill in the art. One exemplary hydraulicsystem for unfolding the detector panels comprises a reversibleelectrical motor to drive a hydraulic pump that in turn provideshydraulic fluid under pressure to a double acting hydraulic actuatorattached to the trailer. When the hydraulic actuator is required tounfold the detector panel, pressurized hydraulic fluid is pumped intothe chamber, engaging a piston to move a slider ball that in turnunfolds the detector panel. Once the detector panel is unfolded throughan acceptable angle, the detector panel is securely latched in positionusing a mechanical latch such as a simple hook and peg system or anyother latching arrangement known to one of ordinary skill in the art. Asimilar arrangement can be used to deploy the remaining detector panels.

FIG. 17 depicts a top view of the single boom cargo scanning system ofthe present invention, in a partially deployed or “partially unfolded”position. Outer arm 1701 is visible and open, thus forming angle 1702with respect to trailer 1703. In one embodiment, the radiation sourcebox (not shown) is located on the same single boom as the detector boxes(as described above) eliminating the need for sophisticated alignmentsystems each time the system is deployed. Thus, the radiation source ispermanently fixed in alignment relative to the detector boom. Theradiation source is located on one side of the boom while the detectorsare located on the other. The rotating boom allows for the source ofradiation to be positioned opposite the area of the boom supporting thedetectors. The radiation source is rotated from a stored or stowedposition to a deployed position. The electrical power generator isturned on to provide power to the electrical devices in the system.While the generator is deployed, the detectors are unfolded as describedabove.

Referring back to FIG. 16, extension and withdrawal of telescopic arm1616 in relation to the main body 1613 is preferably effectuatedhydraulically using suitable hydraulic cylinders (not shown) in mainbody 1613. Thus, telescopic arm 1616 moves with multiple degrees offreedom. FIG. 18 depicts one exemplary movement of the telescopic arm1801 of the single boom cargo scanning system of the present invention.Telescopic arm 1801 forms an acute angle 1802 with respect to outer arm1803. In FIG. 19, another degree of freedom of the abovementionedtelescopic arm is depicted. The telescopic arm 1901 is at aperpendicular 1902 to the outer arm 1903.

As described in detail above, the detectors optionally comprise panelsthat are capable of being folded, such that, when in a storage position,the detectors recess into the side of the inspection trailer. By formingdetectors such that they can fold in a storage position, it is possibleto produce a compact trailer that can safely, and legally, travelroadways. When unfolded during operation, the detectors assume either alinear or an arched shape.

Now referring to FIG. 20, a rear view illustration of the single boomcargo scanning system of the present invention is depicted. As mentionedabove, connecting structure 2001 and outer arm 2002 consist of detectorarray panels 2003. In one embodiment, the detectors assume anapproximate inverted “L” shape, as they are placed on connectingstructure 2001 and outer arm 2002. The inverted “L” shape detectorenables the radiation source to be closer to the target vehicle, thusallowing higher penetration capability, and provides for completescanning of the target vehicle without corner cutoff.

At its distal end, the telescopic arm 2005 is attached to radiationsource 2006 and is deployed from boom 2007, once rotated into desiredscanning positions. Single boom 2007 allows for source 2006, positionedat the base of the telescopic arm 2005, to rigidly align with detectorarray 2003.

An array of laser pointers emitting laser radiation is built into thecollimator to facilitate proper alignment of the radiation beam with thedetectors. In one embodiment, optical triangulation method is used foraligning the plane of the radiation beam with a predefined “zero” or“idealized centerline” of the detector system. Such opticaltriangulation techniques, as known to a person of ordinary skill in theart, use a source of light such as a laser pointer to define theradiation beam path. These laser pointers are directed to impinge on apredefined “zero” of the detectors. The “zero” of the detectors may be aspot representing the centroid of the detector system or an idealizedcenterline representing a spatial x-y locus of an ideal fan beam planeintersecting the plane of the detectors substantially orthogonally. Inone arrangement, the spatial position of the laser pointers impinging onthe detectors is sensed by an array of photo-electric diodes of thedetector system that send the corresponding position signals to acomputer housed within the trailer. The computer compares the spatialposition of the laser pointers with a predefined “zero” of the detectorsystem and sends correction control signals to the source box throughthe control cable (attached to the boom) for adjustments until the laserpointers are reasonably lined-up with the detector system.

Radiation source box 2006, attached to telescopic arm 2005, emitspenetrating radiation beam 2008 having a cross-section of a particularshape. Several embodiments for the radiation source, but not limited tosuch embodiments, are described in further detail throughout thespecification and will not be described herein. The more rigid alignmentof radiation source 2006 with detector array 2003 permits the scanningsystem of the present invention to operate with a narrower beam widthand a lower radiation level. Positioning source 2006 at the base oftelescopic arm 2005 also permits a larger field of view relative to theconventional systems having the source on the vehicle. Also, sinceradiation source 2006 is suspended on the distal end of boom 2007, itcan extend as low as six inches off of floor level, shown as 2009, andcan provide the under-carriage view 2010 of OUI 2011.

Optionally, boom 2007 deploys and permits detector array 2003 andradiation source box 2006 to extend outward, preferably resting at anangle of about 10 degrees relative to the plane perpendicular to OUI2011. This permits for easy viewing of dense material and hiddencompartments (not shown). The heaviest material in cargo is usuallylocated at the bottom floor of the truck. For example, in one particularembodiment, a linear accelerator (LINAC) is employed. The zero degreecenter point of the beam is the strongest portion of the beam. In orderto capture scans of the floor level of the truck, the radiation sourcebeam is positioned to orientate 15 degrees downward to detect materialsin the undercarriage and then 30 degrees upward to detect the higherportions of the load. This ensures that the strongest X-rays (at thezero degree position or, center of the X-ray tube) are oriented at thefloor level of the truck, which is critical to the performance of thesystem as the densest and most difficult portion of a truck to image isthe floor level.

Optionally, boom 2007 deploys and permits detector array 2003 andradiation source box 2006 to scan at various heights. In one embodiment,boom 2007, and thus radiation source box 2006, is positioned to scan atstandard truck height. In another embodiment, boom 2007, and thusradiation source box 2006, is set at a position closer to the ground,and is suitable for scanning automobiles. It should be noted that theboom structure 2007, radiation source 2006, and detector array 2003 onthe same single boom can be positioned at any height without the needfor source and detector array realignment.

During the scanning operation, radiation source 2006 and detector array2003 are activated and the scanning trailer is driven over the OUI, suchthat the objects get positioned between the trailer and radiation source2006. In a preferred embodiment, during the scanning operation, thesource and detectors remain stationary and aligned with respect to eachother while mobilized and passed over the OUI. In a preferredembodiment, the motion of the scanner is kept steady and at a constantvelocity. Since, irregularities in the motion of the vehicle may resultin distortions in the scanned image, the motion is preferably made asregular, even and constant as feasible using known control systems suchas by engaging the trailer motor in “auto speed” mode. As described ingreater detail below, the scanning system is manipulated via a closedloop method to automatically correct images for the different speeds ofoperation of the scanning trailer. Such speed control system is acombination of mechanical, electrical, and software design.

Since the source and detector remain in a relative stationary and fixedposition during the scanning process, collimation can be adjusted to anadvantageous minimum such that the fan beam emerging out of thecollimator just covers the detectors. The collimation mechanism employedis preferably a rotating wheel or any other suitable mechanism as knownto the person of ordinary skilled in the art. Referring to FIG. 21, arotating collimation wheel of one embodiment of the present invention isdepicted. Rotating wheel 2101 is used to develop pencil beam 2102, whichpasses through the object. A series of tubular collimators 2103 aredistributed as spokes on rotating wheel 2101. Cross-section of pencilbeam 2102 is substantially rectangular, but is not limited to suchconfigurations. The dimensions of pencil beam 2102 typically define thescatter image resolution, which may be obtained with the system.

As known in the art, X-ray scanning operates on the principle that, asX-rays pass through objects, the radiation gets attenuated, absorbed,and/or deflected owing to a number of different physical phenomena thatare indicative of the nature of the material being scanned. Inparticular, scattering occurs when the original X-ray hits an object andis then deflected from its original path through an angle. These scatterradiations are non-directional and proportional to the total energydelivered in beam path. A narrowly collimated beam will keep the overallradiation dose minimal and therefore also reduce the amount of scatterradiation in the area surrounding the scanner, thereby reducing the“exclusion zone”.

During deployment the inspection trailer is driven to the inspectionsite and the radiation source and detector booms are positioned. Becausethe trailer moves over the OUI, it does not need to be positionedstrategically to allow for high throughput. Rather, the trailer may bedriven over any OUI, located anywhere, given that there is space for theinspection trailer to pass without disrupting port activities. Anotheraspect that may influence the decision of positioning the trailer couldbe the availability of a large enough area, called the “exclusion zone”,around the scanner system. The exclusion zone is an area around thescanner in which general public are not authorized to enter due to thepossibility of their getting exposed to doses of radiations scatteredduring the scanning process. The exclusion area is dependent upon themagnitude of current setting the intensity of the radiation source.

FIG. 22 illustrates a preferred embodiment of the detector array 2201 asemployed in the single boom cargo scanning system of the presentinvention. The detectors 2202 may be formed by a stack of crystals thatgenerate analog signals when X-rays impinge upon them, with the signalstrength proportional to the amount of beam attenuation in the OUI. Inone embodiment, the X-ray beam detector arrangement consists of a lineararray of solid-state detectors of the crystal-diode type. A typicalarrangement uses cadmium tungstate scintillating crystals to absorb theX-rays transmitted through the OUI and to convert the absorbed X-raysinto photons of visible light. Crystals such as bismuth germinate,sodium iodide or other suitable crystals may be alternatively used asknown to a person of ordinary skill in the art. The crystals can bedirectly coupled to a suitable detector, such as a photodiode orphoto-multiplier. The detector photodiodes could be linearly arranged,which through unity-gain devices, provide advantages overphoto-multipliers in terms of operating range, linearity anddetector-to-detector matching. In another embodiment, an area detectoris used as an alternative to linear array detectors. Such an areadetector could be a scintillating strip, such as cesium iodide or othermaterials known in the art, viewed by a suitable camera or opticallycoupled to a charge-coupled device (CCD).

FIG. 23 is a detailed illustration of one preferred embodiment of thedetectors 2300 employed in the detector array 2305, as shown in FIG. 22.The detectors are preferably angled at 90 degrees relative to theradiation source focal point. The radiation scattered from the radiationsource beam is detected by the strategically positioned detectors, thusimproving image quality.

FIG. 24 is a detailed illustration of another preferred embodiment ofthe detectors employed in the detector array shown in FIG. 22, where thedetectors are arranged in a dual row. Detector array 2401 preferablycomprises a dual row of detectors 2402 that are blended together in aninterlacing fashion to allow better resolution using a suitablealgorithm. The focus algorithm provides automatic means to combine theimages resulting from the dual row of detectors 2402, which are athalf-detector offset from each other, into a single row allowing fordouble resolution compared to a single row of detectors. This blendingmethod eliminates jagged edges in the resultant images from the use ofthe two detector rows 2402.

At any point in time when the radiation source is on, the detectors aresnapshots of the radiation beam attenuation in the OUI for a particular“slice” of the OUI. Each slice is a beam density measurement, where thedensity depends upon beam attenuation through the OUI. The radiationdetectors convert the lateral radiation profile of the OUI intoelectrical signals that are processed in an image processing system,housed in the inspection trailer, while the OUI is being conducted pastthe source and the radiation detector.

The X-ray image processing and control system, in an exemplaryembodiment, comprises computer and storage systems which record thedetector snapshots and software to merge them together to form an X-rayimage of the vehicle which may further be plotted on a screen or onother media. The X-ray image is viewed or automatically analyzed by OUIacquisition system such as a CRT or monitor that displays the X-rayimage of the vehicle to an operator/analyst. Alternatively, the OUIacquisition systems may be a database of X-ray images of desiredtargets, such as automobiles, bricks or other shapes that can becompared with features in the image. As a result of this imaging, onlyarticles that were not contained in the reference image of the containeror vehicle are selectively displayed to an operator/analyst. This makesit easier to locate articles that do not correspond to a referencecondition of the container or vehicle, and then to conduct a physicalinspection of those articles. Also, for high-resolution applications,the electronics used to read out the detector signals may typicallyfeature auto-zeroed, double-correlated sampling to achieve ultra-stablezero drift and low-offset-noise data acquisition. Automatic gain rangingmay be used to accommodate the wide attenuation ranges that can beencountered with large containers and vehicles.

FIG. 25 is a block diagram of an exemplary X-ray image processing anddisplay unit of the single boom cargo scanning system of the presentinvention. X-ray image display and processing unit 2500 includesdetectors 2501 coupled through data processing units (DPU) 2502, drivers2503, interface card 2504 and computing device 2505. Computing device2505 processes discrete photo current integration information receivedfrom the detectors 2501 via interface card 2504, which is attached tocomputing device 2505. Display device 2506, attached to computing device2505, renders the image of the contents of the target object uponreceiving information from computing device 2505. The detector arrayincludes a plurality of detectors. The detectors 2501 are coupled ingroups of data processing circuits (not shown). It is preferred thatthree groups of detectors 2501 are employed, wherein the number ofdetectors 2501 in use is dependent upon the height of the OUI (notshown), and the resolution (i.e. number of pixels) of the image desired.In a preferred configuration, three data processing units 2502 arecoupled to line driver 2503, which is coupled to network interface 2504.Interface 2504, such as but not limited to RS-485, is embodied on acircuit card located within computing device 2505.

Computing device 2505 is preferably a microprocessor based personalcomputer system and operates under the control of a software system.Computing device 2505 thus receives detector pulses 2507 from each ofthe data processing units 2502, in response to the detection ofindividual photons 2508 by the detectors. The software system processesthe incoming detector pulses 2507, evaluates their relative amplitudes(i.e. energies), and generates a radiographic image-like display outputsignal, which is coupled to the graphical display device 2506, thusgenerating a graphical representation of the densities within the OUI.

The present invention generates a graphical representation, i.e., animage, of the densities of the contents of the vehicle under inspection.This allows for easy visual interpretation of the results of thescanning of the OUI.

Advantageously, the preferred software system also causes the display ofa reference image simultaneously with the image generated in response tothe vehicle under inspection, so that an operator of the presentembodiment can easily make a visual comparison between what an object ofthe type being inspected should “look like”, and what the OUI actually“looks like”. Such “side-by-side” inspection further simplifies thedetection of contraband using the present embodiment.

The vertical linear array configuration of the detector array isdesigned to provide a resolution of grid points spaced approximatelyevery 5 cm along the length and about 4.3 cm along the height of thetarget OUI. This resolution is adequate to achieve a detectability limitof less than half a kilogram of contraband per 4.3 cm by 5 cm gridpoint(or pixel). The pixel size can be easily varied by appropriatelyselecting the location of the radiation source and the detectors withinthe detector array, and by varying the distance between inspectionspoints longitudinally (via choice of counting interval and scan speedalong the length of the target vehicle). A suitable algorithm implementsa correction that takes into account the speed of the scanning trailerunder motion, the scanning rate (i.e., number of lines scanned persecond), detector size, and distance between the detectors.

In one embodiment, a closed loop method is employed to automaticallycorrect images for the varying speeds of operation of the scanningsystem. The speed control system is a function of mechanical,electrical, and software components of the scanning system of thepresent invention.

Referring to FIG. 26, a flow chart depicts the operational steps of thesingle boom cargo scanning system of the present invention once theimage generation program is executed. In step 2601, the single boomscanning system of the present invention initiates image generation. Instep 2602, movement of the trailer containing the single boom begins. Inanother embodiment, where the OUI is optionally driven underneath andthrough the self-contained inspection system, start-sensors may bestrategically placed to allow an imaging and control system, locatedwithin the inspection trailer, to determine that the OUI cab, in thecase of a vehicle, has passed the area of beam and the vehicle to beinspected is about to enter the X-ray beam position. Thus, as soon asthe vehicle to be inspected trips the start-sensors, the radiationsource is activated to emit a substantially planar fan-shaped or conicalbeam for the duration of the pass) that is suitably collimated forsharpness and made to irradiate substantially perpendicular to the pathof the vehicle.

In step 2603, the detectors are calibrated by irradiation with theradiation source at a point along the track prior to the radiationsource arm and detector array arm reaching the OUI. In other words,calibration occurs before the OUI is interposed between the detectorarray and the radiation source. The irradiation of the detector arraysets a baseline, in step 2604 of radiation (or “white” photo currentintegration level) analogous to a density in the OUI approximately zeroand a maximum photo current integration level. In step 2605, three photocurrent integration measurements are preferably made in this manner foreach detector. In step 2606, measurements are arranged for each detectorand stored in an array having a white level element for each detector.

In step 2607, the horizontal position is set to zero. The horizontalposition corresponds to a position along the scanning track, randomlyselected, at which density measurements are taken for the first time.This horizontal position should be at a point before the OUI isinterposed between the detector array and the radiation source. In step2608, the detector measurement is set to zero, corresponding to thefirst detector in the detector array to be queried for a photo currentintegration level. The detector is queried in step 2609 for a photocurrent integration level and is instructed to restart measurement. Instep 2610, the detector restarts measurement in response to theinstruction to restart. In step 2611, photo current integration leveldetermined in step 2609 is passed to the measurement device. In step2612, the level of photo current integration measured is stored in anarray and is then converted into a pixel value in step 2613. Theconversion is achieved by mapping the amount of photo currentintegration to a color, for display on the display device. In step 2614,the detector number queried is converted into a vertical position on thescreen display. The horizontal position of the radiation source and thedetector array along the scanning track is converted to a horizontalposition on the screen display in step 2615. Once the vertical andhorizontal positions are ascertained, a pixel is illuminated in step2616 using the color corresponding to the photo current integrationlevel.

In step 2617, a determination is made as to whether all of the detectorsin the detector array have been queried for a photo current integrationlevel for the current horizontal position. If all the detectors have notbeen queried, the detector number to be queried is incremented in step2618. The image generation program continues by querying the nextdetector in the detector array for the photo current integration leveland by instructing such detector to restart measurement as in step 2610.The image generation program continues executing from this step, asdescribed in detail above.

If all the detectors within the detector array have been queried for thecurrent horizontal position, the horizontal position is incremented instep 2619. In step 2620, a determination is made as to whether or notthe radiation source arm and the detector array arm of the single boomscanning trailer are still in motion. If the boom components are stillin motion, the detector to be queried is reset to zero and the imagegeneration program continues, as shown in step 2621. If the single boomscanning system has stopped moving, the image generation program isterminated in step 2622.

As mentioned above, in another embodiment, the present invention isdirected towards a self-contained radiation inspection system and methodfor generating an image representation of target objects using at leasttwo radiation sources of different energies. Thus, the OUI can also beexamined with a multiple energy radiation source or multiple radiationsources having different energies. In one embodiment, the OUI isexamined with two radiation sources having different energies. In oneembodiment, at least one radiation source is a source-based systemcapable of providing gamma radiation. In one embodiment, the twodifferent energies employed are ¹³⁷Cs and ⁶⁰Co, allowing the inspectionsystem to detect materials of both high and low atomic numbers.

In one embodiment, at least one low energy radiation source is employedto allow for imaging of objects having a lower density. In oneembodiment, at least one high energy radiation source is employed toallow for imaging of objects having a higher density. Thus, when a lowerenergy radiation source is employed, it is possible to view objectshaving a low density and when a higher radiation source is employed, itis possible to view high density objects. When used simultaneously, itis thus possible to obtain an image that represents materials and/orobjects having both low and high density.

In addition, the dual energy radiation inspection system of the presentinvention employs the same detector array to separately detect theattenuation of the differing energies impinging upon the OUI, which willalso be described in further detail below.

Referring back to FIG. 13, above, the self-contained inspection system1300 of the present invention comprises, in a one embodiment, aninspection module in the form of a rig/tractor trailer 1301, capable ofbeing driven to its intended operating site. The vehicular portion ofthe system and the inspection module portion of the system areintegrated into a single mobile structure. The integrated modular mobilestructure serves as a support and carrier structure for at least onesource of electromagnetic radiation; and a possible radiation shieldplate on the back of the driver cabin of the vehicle, used to protectthe driver from first order scatter radiation.

The inspection or scanning module 1300 is custom-built as an integratedmobile trailer 1301 and can provide support for a single boom 1302 todeploy a power cable (not shown) to at least one source of radiation1304 during operation. In one embodiment, the at least one source ofradiation is capable of emitting radiation of at least one energy typeor level. In one embodiment, the at least one source of radiation iscapable of emitting radiation in two different energies. In anotherembodiment, the inspection or scanning module 1300 can provide supportfor two sources of radiation 1304. The structural characteristics of theself-contained mobile inspection system have been described above withrespect to FIGS. 13-26 and will not be repeated herein, except todescribe operational characteristics of the present invention.

Referring back to FIG. 13, radiation source box 1304 is located on thesame single boom 1302 as the detection system 1303. Radiation source box1304 is located opposite the detector system 1303 at a distance that issuitable to allow an Object under Inspection (“OUI”) to pass in the area1306 between the source 1304 and detector array 1303 during the scanningprocess, it is located on the same boom 1302 to eliminate the need foralignment. If the radiation source box is mounted on the same singleboom as the detector arrays, the need for sophisticated alignmentsystems each time the system is deployed is eliminated. Thus, theradiation source box and detectors are substantially permanently alignedon the same single boom. The feature also allows for scanning at variousdegrees of offset, again without the need to realign the radiationsource and detectors.

The source of radiation includes a radio-isotopic source, an X-ray tube,LINAC or any other source known in the art capable of producing beamflux and energy sufficiently high to direct a beam to traverse the spacethrough an OUI to detectors at the other side. The choice of source typeand its intensity and energy depends upon the sensitivity of thedetectors, the radiographic density of the cargo in the space betweenthe source and detectors, radiation safety considerations, andoperational requirements, such as the inspection speed.

In one embodiment, radiation source box 1304 comprises two sources ofradiation having different energies. For example, but not limited tosuch example, the present invention employs two source-based systems,such as ⁶⁰Co and ¹³⁷Cs and further employ the required photomultipliertubes (PMT) as detectors. If a linear accelerator (LINAC) is optionallyemployed, then photodiodes and crystals are used in the detector. One ofordinary skill in the art would appreciate how to select a radiationsource type, depending upon his or her inspection requirements.

In one embodiment, ⁶⁰Co is used as a first gamma ray source and has ahigh specific activity of the order of 11.1 TBq (300 Ci) and a lineardimension of the active area of 6 mm. In one embodiment, the secondgamma ray source is a 1.0, 1.6 or 2.0 Curie shuttered mono-energeticsource of ¹³⁷Cs gamma rays, having a 662 keV energy.

In another embodiment, a nearly mono-energetic ⁶⁰Co gamma ray source isused, which is capable of emitting photons at two distinct energylevels, more specifically, 1170 an 1339 KeV. In one embodiment, thegamma rays emitted from the ⁶⁰Co source are collimated by their slits toform a thin fan-shaped beam with a horizontal field angle of 0.1° and avertical field angle of 65°.

FIG. 27 is a schematic representation of a dual energy radiation sourceas employed in the self-contained mobile inspection system of thepresent invention. Now referring to FIG. 27, radiation source box 2700comprises first gamma radiation source 2701 and second gamma radiationsource 2702, which in one embodiment, are of different energies. In oneembodiment, first gamma radiation source 2701 is ⁶⁰Co. In oneembodiment, the second gamma radiation source 2702 is ¹³⁷Cs. It shouldbe understood by those of ordinary skill in the art that first andsecond gamma ray sources are interchangeable and are not limited to theembodiments presented herein.

As mentioned above, in one embodiment, at least one low energy radiationsource is employed to allow for imaging of objects having a lowerdensity. In one embodiment, at least one high energy radiation source isemployed to allow for imaging of objects having a higher density. Thus,when a lower energy radiation source is employed, it is possible to viewobjects having a low density and when a higher radiation source isemployed, it is possible to view high density objects. When usedsimultaneously, it is thus possible to obtain an image that representsmaterials and/or objects having both low and high density.

In operation, in one embodiment, first gamma radiation source 2701 andsecond gamma radiation source 2702, having different energies,alternately irradiate the OUI (not shown). Thus, both high energytransmission rays and low energy transmission rays alternately strikethe OUI (not shown). In another embodiment, first gamma radiation source2701 and second gamma radiation source 2702, having different energies,simultaneously irradiate the OUI with both energies. In one embodiment,the detector electronics, described in greater detail below, areemployed to separate the individual responses of the two energiesstriking the OUI.

As described above, in one embodiment, radiation source box 2700 islocated on a trailer (not shown), but not fixedly connected to the boom(not shown). In this embodiment, the radiation source box is towed tothe deployment site and positioned on a movable platform for use. Thisembodiment is described in detail above with respect to FIGS. 1-12 andwill not be repeated herein. Also, as described above with respect toFIGS. 13-26, and not described further herein, the radiation source box2700 of the present embodiment is located on the distal end of thesingle structural boom fixedly connected to the trailer. In oneembodiment, the two sources of different energies are housed indifferent radiation source boxes. In another embodiment, the two sourcesof different energies are physically located in a common housing orradiation source box.

The X-ray image processing and control system comprises computer andstorage systems which record the detector snapshots and software tomerge them together to form an X-ray image of the vehicle which mayfurther be plotted on a screen or on other media. In one embodiment, twoimages are generated that represent recorded detector snapshots of thedata from different energy sources. More specifically, one image wouldbe generated for the higher energy source while another image would begenerated from the lower energy source. The operator is then able to usethe resultant images to view different densities for the same portion ofthe OUI.

In another embodiment, suitable algorithms are employed to combine theresultant images generated by the lower energy and higher energyradiation sources to obtain additional information. The X-ray image orX-ray images are viewed or automatically analyzed by OUI acquisitionsystem such as a CRT or monitor that displays the X-ray image of thevehicle to an operator/analyst.

Alternatively, the OUI acquisition systems may be a database of X-rayimages of desired targets, such as automobiles, bricks or other shapesthat can be compared with features in the image. As a result of thisimaging, only articles that were not contained in the reference image ofthe container or vehicle are selectively displayed to anoperator/analyst. This makes it easier to locate articles that do notcorrespond to a reference condition of the container or vehicle, andthen to conduct a physical inspection of those articles. Also, forhigh-resolution applications, the electronics used to read out thedetector signals may typically feature auto-zeroed, double-correlatedsampling to achieve ultra-stable zero drift and low-offset-noise dataacquisition. Automatic gain ranging may be used to accommodate the wideattenuation ranges that can be encountered with large containers andvehicles.

FIG. 28 is a block diagram of an exemplary gamma-ray image processingand display unit of the self-contained mobile inspection system of thepresent invention. Gamma-ray image display and processing unit 2800includes detectors 2801 coupled through data processing units (DPU)2802, first temporary storage unit (TSU) 2809, second temporary storageunit 2810, drivers 2803, interface card 2804 and computing device 2805.Computing device 2805 processes discrete photo current integrationinformation received from the detectors 2801 via interface card 2804,which is attached to the computing device 2805. Display device 2806,attached to computing device 2805, renders the image of the contents ofthe target object upon receiving information from computing device 2805.

The detector array includes a plurality of detectors. The detectors 2801are coupled in groups of data processing circuits (not shown). In oneembodiment, three groups of detectors 2801 are employed, wherein thenumber of detectors 2801 in use is dependent upon the height of the OUI(not shown), and the resolution (i.e. number of pixels) of the imagedesired.

In one configuration, three data processing units 2802 are coupled to afirst temporary storage unit 2809 and a second temporary storage unit2810 and a line driver 2803. The temporary storage units 2809, 2810 areused to store the detector pulses 2807, 2811 generated by two radiationsources having different energies (not shown). In one embodiment, thedetector pulses 2807, 2811 are generated at different intervals of time,or alternately. Once both detector pulses 2807, 2811 generated from thefirst radiation source and the second radiation source are received bythe first temporary storage unit 2809 and the second temporary storageunit 2810, respectively, they are forwarded to the line driver forsuitable conversion and transmission.

The line driver 2803 is coupled to a network interface 2804. Interface2804, such as but not limited to RS-485, is embodied on a circuit cardlocated within computing device 2805. Computing device 2805 is amicroprocessor based personal computer system and operates under thecontrol of a software system. Computing device 2805 thus receivesdetector pulses 2807, 2811 from each of the data processing units 2802,in response to the detection of individual photons 2808 by thedetectors. In the present embodiment, multiple radiation sourcesre-illuminate the detector alternately and thus enable the computingdevice 2805 to store the detector pulses 2807 and 2811 for futureprocessing using a suitable algorithm.

In another embodiment, multiple radiation sources illuminate thedetector simultaneously and enable the computing device 2805 to storethe detector pulses 2807 and 2811 for future processing using a suitablealgorithm. In this case, the DPU 2802 would be capable of separating thedetector pulses 2807 and 2811 for the two energies.

The software system processes the incoming detector pulses 2807,evaluates their relative amplitudes (i.e. energies), and generates aradiographic image-like display output signal, which is coupled to thegraphical display device 2806, thus generating a graphicalrepresentation of the densities within the OUI.

The present invention advantageously uses a combination of two distinctimages generated by the detection of radiation at two different energiesto generate a graphical representation, i.e., an image, of the densitiesof the contents of the vehicle under inspection. This allows for easyvisual interpretation of the results of the scanning of the OUI.

In addition, the software system causes the display of a reference imagesimultaneously with the image generated in response to the vehicle underinspection, so that an operator of the present embodiment can easilymake a visual comparison between what an object of the type beinginspected should “look like”, and what the OUI actually “looks like”.Such “side-by-side” inspection further simplifies the detection ofcontraband using the present embodiment.

The vertical linear array configuration of the detector array isdesigned to provide a resolution of grid points spaced approximatelyevery 5 cm along the length and about 4.3 cm along the height of thetarget OUI. This resolution is adequate to achieve a detectability limitof less than half a kilogram of contraband per 4.3 cm by 5 cm gridpoint(or pixel). The pixel size can be easily varied by appropriatelyselecting the location of the radiation source and the detectors withinthe detector array, and by varying the distance between inspectionspoints longitudinally (via choice of counting interval and scan speedalong the length of the target vehicle). A suitable algorithm implementsa correction that takes into account the speed of the scanning trailerunder motion, the scanning rate (i.e., number of lines scanned persecond), detector size, and distance between the detectors.

The configuration of the detector array has been described in greatdetail above with respect to FIGS. 1-26 and thus, will not be repeatedherein. In one embodiment, an array of 1.125 inch detectors is employed.In one embodiment, an array of 0.625 inch detectors is employed. Theadvantage of using a 0.625 inch detector is enhanced resolutionperformance of the system. In one embodiment, a closed loop method isemployed to automatically correct images for the varying speeds ofoperation of the scanning system. The speed control system is a functionof mechanical, electrical, and software components of the scanningsystem of the present invention.

FIG. 29 is a flow chart depicting the operational steps of theself-contained mobile inspection system employing a dual energyradiation source upon the execution of an image generation program. Instep 2901, the single boom scanning system of the present inventioninitiates image generation. In step 2902, movement of the trailercontaining the single boom begins. In another embodiment, where the OUIis optionally driven underneath and through the self-containedinspection system, start-sensors may be strategically placed to allow animaging and control system, located within the inspection trailer, todetermine that the OUI cab, in the case of a vehicle, has passed thearea of beam and the vehicle to be inspected is about to enter thegamma-ray beam position. Thus, as soon as the vehicle to be inspectedtrips the start-sensors, both the radiation sources are activated toemit substantially planar fan-shaped or conical beam for the duration ofthe pass) that is suitably collimated for sharpness and made toirradiate substantially perpendicular to the path of the vehicle.

In step 2903, the detectors are calibrated by irradiation with at leastone radiation source at a point along the track prior to the OUIreaching the area between the radiation source and detector array.Preferably, the detectors are calibrated prior to scanning the OUI. Inone embodiment, the detectors are calibrated for two different energiesand a baseline is recorded by the software and stored in the memory ofthe system.

The irradiation of the detector array sets a baseline of radiation (or“white” photo current integration level), in step 2904, analogous to anapproximately zero density in the OUI and a maximum photo currentintegration level. In step 2905, three photo current integrationmeasurements are made in this manner for each detector. In step 2906,measurements are arranged for each detector and stored in an arrayhaving a white level element for each detector.

In step 2907, the horizontal position is set to zero. The horizontalposition corresponds to a position along the scanning track, randomlyselected, at which density measurements are taken for the first time.This horizontal position should be at a point before the OUI isinterposed between the detector array and the radiation source. In step2908, the detector measurement is set to zero, corresponding to thefirst detector in the detector array to be queried for a photo currentintegration level. The detector is queried in step 2909 for a photocurrent integration level and is instructed to restart measurement. Instep 2910, the detector restarts measurement in response to theinstruction to restart. In step 2911, the photo current integrationlevel determined in step 2909 is passed to the measurement device. Instep 2912, the level of photo current integration measured is stored inan array and is then converted into a pixel value in step 2913. Theconversion is achieved by mapping the amount of photo currentintegration to a color, for display on the display device. In step 2914,the detector number queried is converted into a vertical position on thescreen display. The horizontal position of the radiation source and thedetector array along the scanning track is converted to a horizontalposition on the screen display in step 2915.

Once the vertical and horizontal positions are ascertained, a pixel isilluminated in step 2916 using the color corresponding to the photocurrent integration level. The pixel value is calculated by taking theaverage of both the horizontal positions and vertical positions obtainedby the illumination of OUI by both the gamma radiation sources, and aredependent on the energy of the source being used.

In step 2917, a determination is made as to whether all of the detectorsin the detector array have been queried for a photo current integrationlevel for the current horizontal position. If all the detectors have notbeen queried, the detector number to be queried is incremented in step2918. The image generation program continues by querying the nextdetector in the detector array for the photo current integration leveland by instructing such detector to restart measurement as in step 2910.The image generation program continues executing from this step, asdescribed in detail above.

If all the detectors within the detector array have been queried for thecurrent horizontal position, the horizontal position is incremented instep 2919 and the image generation program continues, as shown in step2920. In step 2921, a determination is made as to whether or not all thedetectors have been queried by the second radiation source. If thedetectors have not been queried by the second radiation source, thedetectors to be queried are calibrated again by irradiating with thesecond source, as shown in step 2903. The image generation programcontinues executing from this step, as described in detail above.

In step 2922, a determination is made as to whether or not the radiationsource arm and the detector array arm of the single boom scanningtrailer are still in motion. If the boom components are still in motion,the detector to be queried is reset to zero and the image generationprogram continues, as shown in step 2920. If the single boom scanningsystem has stopped moving, the image generation program is terminated instep 2923.

FIG. 30 is a top view illustration of the radiation safety exclusionzone and dosage areas surrounding the scanning system of the presentinvention. In one embodiment, the radiation exclusion zone is reduced bypositioning a lead shield behind the detector array and on the singleboom column, as described in further detail below. The lead shield actsas a radiation beam stop and significantly reduces the operating area ofthe system. As shown in FIG. 30, the area 3001 of the radiation beam isblocked due to the lead shield assembly mounted behind the detectorarray.

In one embodiment, the driver inside truck cab 3002 incurs a dose rateof less than 50 microrems per hour when the radiation source is in anopen and active position. In one embodiment, the operators inside thecabin on the rear seat 3003 behind the driver incur a dose rate of lessthan 60 microrems per hour. The portion with the highest radiationexposure is shown as the area within boundary 3005, and has a dose rateof more than 120 microrems per hour. Area 3007, outside of but proximateto boundary 3005, has a dose rate of less than 120 microrems per hour.

Optionally, the inspection system of the present invention may includeadditional safety measures, such as but not limited to at least onecamera proximate to the inspection system to present a view of the areasurrounding the inspection system on the monitor inside the operatorcabin. In one embodiment, four cameras are employed and positioned atdifferent angles to offer a 360° view to the operator inside the cabin,as shown in FIG. 30, to monitor the exclusion zone.

In another embodiment, the radiation source box of the present inventionincludes a safety shut-off. In one embodiment, the safety shut-off isenabled when an object that is not under inspection enters the exclusionzone. In one embodiment, the safety shut-off is manual and an operatorcan thus power down the system if there is suspicious activity in theexclusion zone. In another embodiment, the safety shut-off is operablyconnected to a motion detector system which will power down the systemin the event of an exclusion zone breach.

The above examples are merely illustrative of the many applications ofthe system of present invention. Although only a few embodiments of thepresent invention have been described herein, it should be understoodthat the present invention might be embodied in many other specificforms without departing from the spirit or scope of the invention. Forexample, other configurations of cargo, tires, tankers, doors, airplane,packages, boxes, suitcases, cargo containers, automobile semi-trailers,tanker trucks, railroad cars, and other similar objects under inspectioncan also be considered. Therefore, the present examples and embodimentsare to be considered as illustrative and not restrictive, and theinvention is not to be limited to the details given herein, but may bemodified within the scope of the appended claims.

1. A portable inspection system for generating an image representationof target objects using a radiation source, comprising: a. a housingconnected to a vehicle; b. a detector array having a first configurationand a second configuration wherein said array is connected to thehousing; and c. at least one source of radiation wherein said radiationsource is capable of being transported to a site by said vehicle and ofbeing positioned separate from the housing, wherein said radiationsource is housed in a radiation source box and movable within theradiation source box using an actuator wherein the actuator is operablyconnected to the radiation source and wherein the actuator provides atranslational energy that moves the radiation source between anoperational position and a stowed position.
 2. A portable inspectionsystem for generating an image representation of target objects using aradiation source, comprising: a. a foldable boom comprising a firstvertical portion, which is physically attached to said vehicle, a firsthorizontal portion, and a second vertical portion; b. a first detectorarray housing physically attached to the first horizontal portion of thefoldable boom, wherein said first detector array housing contains aplurality of detectors; c. a second detector array housing physicallyattached to the first vertical portion of the foldable boom wherein thesecond detector array housing contains a plurality of detectors and isfoldable independent of said first vertical portion of the foldableboom; and d. at least one source of radiation wherein said radiationsource is housed in a radiation source box and movable within theradiation source box using an actuator, wherein the actuator is operablyconnected to the radiation source, wherein the actuator provides atranslational energy that moves the radiation source between anoperational position and a stowed position, and wherein the radiationsource box is securely attached to a distal end of the second verticalportion of said boom.
 3. The system of claim 2 wherein the radiationsource is movable in a horizontal or vertical direction.
 4. The systemof claim 2 wherein the actuator is an electric solenoid.
 5. The systemof claim 2 wherein the actuator is a pneumatic solenoid.
 6. The systemof claim 2 wherein the radiation source is offset from a beam portaperture defined by the radiation source box when in a stowed position.7. The system of claim 6 wherein the radiation source is offset from abeam port aperture by three inches.
 8. The system of claim 6 wherein theradiation source is encapsulated in a shield when offset from a beamport aperture.
 9. The system of claim 8 wherein the shield comprisestungsten.
 10. The system of claim 2 wherein the radiation source isaligned with a beam port aperture defined by the radiation source boxwhen in an operational position.
 11. The system of claim 2 wherein theradiation source box further comprises a return mechanism for ensuringthat the radiation source is in a safe position when there is no powerbeing delivered to the system.
 12. The system of claim 2 wherein theradiation source box further comprises at least one safety feature forindicating a status of the radiation source.
 13. The system of claim 12wherein the safety feature is electrical and further comprises a light.14. The system of claim 12 wherein the safety feature is audible andfurther comprises a beeping alarm.
 15. The system of claim 12 whereinthe safety feature is mechanical and further comprises a flag.
 16. Thesystem of claim 2 further comprising a hydraulic system to move theboom.
 17. The system of claim 2 wherein said first and second detectorarrays comprise detectors and wherein said detectors are angled atsubstantially 90 degrees relative to a focal point of said radiationsource.
 18. The system of claim 2 wherein said radiation sourcecomprises at least a first energy and a second energy.
 19. The system ofclaim 18 wherein the first energy is a low energy and wherein the secondenergy is a high energy.